Alert November 28, 2012

America (re)Invents Alternatives to Patent Litigation

Following the enactment of the America Invents Act (“AIA”), U.S. patent owners and potential patent challengers have no shortage of options for post-issuance patent review. Because the risks and benefits of the available procedures depend on a party’s strategic perspective, it is informative to view the procedures from two perspectives – that of a patent challenger, and that of a patent owner. Challengers now have four distinct administrative routes for invalidating issued patents: inter partes review, post-grant review, ex parte reexamination and derivation. A transitional program for covered business method patents is also available. Patent owners have four options for correcting an issued patent or preemptively addressing prior art before enforcement: ex parte reexamination, supplemental examination, reissue and certification of correction. In this article we provide an overview of post-issuance proceedings new and old, and consider the tradeoffs of each procedure to assist challengers and patent owners in making informed strategic decisions.

Tables A and B, links below, provide a summary of the proceedings available to challengers and patent owners.

Table A – Post-Issuance PTO Proceedings Available to Challengers

Table B – Post-Issuance PTO Proceedings Available to Patent Owners 


 As described above, patent challengers now have five options (including a transitional program) for requesting post-issuance review under the AIA. The advantages and disadvantages of these procedures, relative to litigation and to each other are discussed below. Table A provides a summary of review procedures available to challengers.

Inter Partes Review: Revamping Inter Partes Re-examination

Inter partes review (“IPR”) is a completely new option available under the AIA. In many ways, IPR is similar to inter partes reexamination, which was available until September 16, 2012. There are, however, certain significant differences, such as the availability of limited discovery in IPR. Unlike inter partes reexamination, IPR is available for any patent whether or not it issued from an application filed on or after November 29, 1999. IPR is also available for patents issuing from applications filed under both the first-to-invent regime and those filed under the first-inventor-to-file (“FITF”) regime that takes effect on March 16, 2013. This is an advantage compared to the post-grant review procedure, discussed below, which is available only for patents issuing from applications filed under the FITF regime. Other advantages and disadvantages of IPR are summarized in Table 1.

Table 1: Advantages and Disadvantages of IPR

 Advantages  Disadvantages
  • Preserve some defenses for litigation
    Good likelihood of complete success (based on inter partes reexamination success rate)
  • High likelihood of some clarification/file history estoppel
  • Lower burden of proof than litigation
  • Speed (1 year from date of acceptance)
  • Direct appeal to Federal Circuit
  • Likelihood of litigation stay
  • Discovery
  • Adversarial Proceeding
  • Claim amendments remove past damages or can invoke intervening rights
  • Decision by patent experts rather than district court judge or jury
  • Estoppel
  • Cost is high, probably akin to interference practice (~$600,000+ for a complicated case with many claims and many prior art arguments)
  • Cannot file subsequent requests
  • Risk of countersuit by patentee (cannot file anonymously)
    Risk of “gold plating” the patent
  • Claims can be amended
  • Page limits
  • Only available nine months or more after patent issuance


In IPR, a challenger may seek to invalidate the claims of a patent under 35 U.S.C. §§ 102 or 103, i.e., by showing that one or more prior art references anticipates or renders obvious the challenged claims. The challenger may rely only on issued patents and printed publications, and not on other prior art such as prior sale of a product or public use thereof. After a final, written decision issues with respect to a challenged claim, the challenger is estopped from contending in any civil action or any ITC proceeding under the Tariff Act that the claim is invalid under any ground that was raised or reasonably could have been raised during IPR.

Pre-AIA, a challenger who opted for inter partes reexamination was estopped from challenging validity in a subsequent civil action on any ground that could have been raised before the U.S. Patent & Trademark Office (“PTO”). Now, a challenger who pursues IPR is only barred from raising grounds that “reasonably” could have been raised in the earlier proceeding. Until courts have an opportunity to interpret the new standard, however, it is unclear what practical benefit the new reasonableness limitation offers challengers. It is not hard to imagine a district court finding “unreasonable” a challenger’s failure to obtain any prior art publication that was available at least somewhere at the time of the IPR. Moreover, the estoppel effect of IPR applies not only to civil actions but also to ITC proceedings and subsequent PTO challenges. To reduce estoppel risk, the challengers must ensure that invalidity contentions based on all applicable prior art references and suitable combinations thereof are presented in the IPR request.

IPR has several other disadvantages – most notably, its high cost. The filing fee is $27,500 for requesting review of 20 or fewer claims, and $600 for each additional claim. Based on the typical cost of inter partes reexamination, the overall cost of IPR, including attorney’s fees, may be as much as $600,000 for a relatively complex patent with numerous claims and several prior art challenges. Another disadvantage is that a challenger cannot file another IPR petition or even an ex parte reexamination request after a decision issues in the first filed IPR. Additionally, any civil action initiated by the challenger is automatically stayed by initiation of an IPR. By contrast, civil actions initiated by the patentee are not stayed automatically – and because a challenger in an IPR proceeding cannot be anonymous, a challenger who chooses IPR over ex parte reexamination (where anonymity is permitted) faces a much higher risk of being targeted in a lawsuit by the patentee. A challenger also runs the risk that IPR will “gold plate” the patent because the patentee may take advantage of the additional time before the PTO to amend claims to avoid the cited art (and, as described above, the challenger may be foreclosed from asserting any additional patents and publications). Furthermore, as the identity of the challenger would be known, the patentee may narrow the claims so as to avoid the cited art but to cover the challenger’s products. Although generally, the PTO must give the claims their broadest reasonable meaning in light of the specification, IPR affords patentees the opportunity to inform claim construction by submitting affidavits from practitioners of the related technology and reports from experts in the field.

A final disadvantage is the page limit – a new restriction that did not apply to inter partes reexamination. A petition for IPR is limited to 60 pages. By comparison, a typical inter partes reexamination request based on three or four primary references and several secondary references often reached 200 pages. As such, it may be virtually impossible to address all permissible grounds for invalidity in the much shorter petition for IPR, which is quite a concern given the strict estoppel. As described above, the challenger may be estopped from contending grounds omitted in the IPR petition during a subsequent proceeding. The challenger may state all grounds exceeding the page limit, and may request a waiver of the page limit. If that request is denied, and if the Patent Trial and Appeal Board (“PTAB”) refuses to consider all grounds for invalidity, according to the language of the statute the challenger may still be estopped from asserting those grounds in a subsequent proceeding. One way to address this issue may be to challenge only some of the independent claims and a few selected dependent claims in the IPR, because estoppel does not apply to the unchallenged claims. If a certain claim is found to be invalid, during a subsequent proceeding issue preclusion (collateral estoppel) may be invoked to assert invalidity of a similar independent claim.

IPR also offers significant benefits, particularly as compared to litigation. Indeed, IPR combines some of the advantages of litigation, such as discovery (including expert reports), with those of inter partes reexamination, such as amendment of claims. From a challenger’s perspective, there is a good likelihood of complete success, i.e., all claims may be invalidated or require amendment due to the adversarial nature of the process. In the case of “substantial” change to the claims, the challenger is not liable for past damages even if the challenger’s products are found to infringe the amended claims (see 35 U.S.C. § 252). Whereas litigation requires demonstration of invalidity by clear and convincing evidence, invalidity can be established at the PTO by a preponderance of the evidence. In addition, IPR is conducted by the PTAB, which not only offers familiarity with patent law but often subject matter expertise as well; this may improve the odds that a challenger will prevail on invalidity. Other benefits include a relatively quick resolution because the PTAB must determine whether to institute a review within six months after the petition for review is filed, and must render a final decision within one year thereafter, if the review is instituted. Only for good cause can the final decision be rendered after an additional six-month period. Claim construction can be informed via the limited discovery that is available to both the patentee and the challenger. Information about design choices, which may be relevant to obviousness of certain claim limitations, can also be sought via discovery. Because IPR is an adversarial process, these issues can be further explored during cross examination at trial before the PTAB. In addition, the patentee’s statements become part of the file history, preventing the patentee from taking inconsistent positions during any subsequent proceedings. Another benefit of IPR is that adverse decisions can be directly appealed to the Federal Circuit.

One final advantage of IPR, as compared with post-grant review (discussed below), is that the grounds for invalidity in the IPR are limited to anticipation and obviousness based on patents and printed publications only. Invalidity cannot be challenged based on §§ 101 and 112 (i.e., non-patentable subject matter, indefiniteness, lack of written description, and lack of enablement). Invalidity cannot be asserted based on prior sale or use of a product either. Therefore, the challenger is not estopped from asserting these grounds for invalidity in a subsequent proceeding.

Post-Grant Review: Powerful but Risky – Use Only as Directed

Procedurally similar to IPR in some respects, post-grant review (“PGR”) also has significant differences, both procedural and substantive, that impact the tradeoffs a challenger must make in choosing between proceedings. PGR is available only for patents issuing from applications filed under the FITF regime, which will become effective on the critical date of March 16, 2013. For an application to fall under the FITF regime, at least one claim must not be able to claim priority to a date earlier than the critical date. Typically, many patents that would issue in the months after the critical date may have been filed before the critical date, and many more may claim priority to other applications filed before the critical date. As such, in order to seek PGR of a patent that may issue over the next several months, the challenger may first have to show that at least one issued claim cannot claim priority to a date earlier than the critical date. It is unclear if a challenger is permitted to make this showing in its petition, or whether the PTO will make the determination without external input. Therefore, it may be that PGR will not be widely used until the issuance of patents that clearly fall under the FITF regime. The advantages and disadvantages of PGR are summarized in Table 2. Differences from IPR are emphasized.

Table 2: Advantages and Disadvantages of PGR

 Advantages   Disadvantages 
  • Broad grounds of attack, including indefiniteness and non-statutory subject matter
  • Can be filed immediately after patent grant
  • High likelihood of some clarification/file history estoppel
  • Lower burden of proof than litigation
    Speed (1 year from date of acceptance)
  • Direct appeal to Federal Circuit
  • Likelihood of litigation stay
  • Discovery
  • Adversarial Proceeding
  • Substantial claim amendments remove past damages
  • Decision by patent experts rather than district court judge or jury 
  • Broad range of estoppel (including indefiniteness, written description, invalidity based on sale or use or a prior art product, etc.)
  • May cost even more than IPR
  • Cannot file subsequent requests
  • Risk of countersuit by patentee (cannot file anonymously)
  • Risk of “gold plating” the patent
  • Claims can be amended
  • Page limits
  • Must be filed within nine months after patent issuance 


One major feature that distinguishes PRG from IPR is that PGR can be requested immediately after a patent issues. Because the Federal Circuit has significantly raised the bar for establishing willful infringement in recent years, a challenger now has an incentive to monitor competitor patent portfolios with relatively lower risk of incurring treble damages in court. A challenger can more safely consider the claimed subject matter and disclosures in a competitor’s patent to improve its own pending applications. Alternatively, if the challenger determines with a high degree of confidence that at least some of the claims of an issued patent are invalid, particularly in light of what was known by the public at the time of the alleged invention by way of use or sale of a product, the challenger may seek to invalidate that patent immediately using PGR.

PGR also offers more grounds for invalidating a patent than either IPR or ex parte reexamination. PGR allows a challenger to show invalidity under § 101, for claiming abstract, non-patentable subject matter, or under § 112 for indefiniteness, lack of written description, and lack of enablement. PGR even allows a challenger to submit evidence of prior sale or use under §§ 102 and 103.

These additional grounds to show invalidity are highly useful, for example, if a prior art patent or publication is not as strong a reference as a prior art product. Limited discovery similar to that available under IPR is available under PGR. If the prior art is a product or a method sold or used, discovery and cross-examination can be used by a challenger to obtain technical documentation and information about dates of sale and use.

Discovery and cross-examination are particularly beneficial if the prior art is a product that is sold or used or a method that is practiced, because the challenger can obtain documentation about such products and depose witnesses on issues such as product features and dates of sale and use. Moreover, in order to overcome a challenge under §§ 101 and 112, the patentee may have to present arguments and explain the claim terms, and alternatively or in addition, amend certain claim terms. These statements would become part of the intrinsic record for the patent, preventing the patentee from making inconsistent arguments during a subsequent proceeding.

However, the additional grounds of invalidity that are available under PGR present a double-edged sword: the challenger risks estoppel as to any claim for which a final written decision issued in any subsequent civil action or ITC proceeding on any ground the challenger raised or “reasonably could have raised.” If the PTO finds a claim to be valid, there are very few options left for a challenger to pursue in court, unless the challenger can come up with a new invalidity theory that it can show it could not have reasonably raised during PGR. Therefore, before seeking PGR, the challenger must know with a very high degree of confidence that it has discovered and applied the applicable prior art references, including patents, publications and products. Discovery is available for only three months, which may impose a practical limit on how much product information can be obtained from documents and witnesses. Even when all applicable art and related information has been found, proving invalidity based on that art may be difficult because the page limit – 80 pages – will restrict the ability of petitioners to adequately address every possible ground.

Transitional Program for Covered Business Method Patents – a New and Useful Tool for Been There, Done That Naysayers

The patents covered under the transitional program for covered business method (“CBM”) patents must claim a method or apparatus for performing data processing or other operations used in the practice, administration or management of a financial product or service, and those patents must not include technological inventions. Procedurally, the transitional program for CBM patents is very similar to PGR. Unlike PGR, however, review of CBM patents can be sought for patents issuing under the first-to-invent regime, and as such, the transitional program is already available. Another distinction with respect to PGR is that to seek review under the transitional program, the challenger must have been accused of infringement. Another important difference is that the estoppel provision in CBM is much less severe than in PGR. The advantages and disadvantages of the transitional program are summarized in Table 3. Differences from IPR and PGR are emphasized.

Table 3: Advantages and Disadvantages of the Transitional Program for CBM Patents

 Advantages   Disadvantages 
  • Broad grounds of attack, including indefiniteness
  • Broad grounds may be particularly advantageous, if not necessary, to challenge business method patents
  • As a matter of fact, can be filed immediately after patent grant
  • High likelihood of some clarification/file history estoppel
  • Lower burden of proof than litigation
  • Speed (1 year from date of acceptance)
  • Direct appeal to Federal Circuit
  • Likelihood of litigation stay
  • Discovery
  • Adversarial proceeding
  • Claim amendments remove past damages
  • Decision by patent experts rather than district court judge or jury
  • Broad range of estoppel (including indefiniteness, written description, invalidity based on sale or use or a prior art product, etc.), however, estoppel is limited only to issues actually raised and does not extend to all issues that could have reasonably been raised as in IPR and PGR.
  • Challenger must have been accused of infringement
  • Cost can be higher than even that of IPR
  • Cannot file subsequent requests
  • Risk of countersuit by patentee (cannot file anonymously)
  • Risk of “gold plating” the patent
  • Claims can be amended
  • Page limits
  • Unclear exactly how “covered business method” will be interpreted by PTAB
  • After 3/16/13, only available nine months or more after patent issuance 


Because the transitional program is substantially the same as PGR, the advantages and disadvantages of PGR discussed above also apply to the transitional program. In particular, a main disadvantage of the transitional program, similar to that of the PGR, is that more grounds for invalidity are available under the transitional program, and, as a consequence, the estoppel effect can be harsher than that resulting from IPR or ex parte reexamination.

PGR is likely to be more attractive to challengers of business method patents than other kinds of inventions. Showing invalidity through IPR or ex parte reexamination is often not feasible with respect to CBM patents, because business methods were not widely pursued in the past, and businesses typically chose to keep their methods secret rather than publish them. But evidence of prior sale or past use, known by industry practitioners, is often easier to track down – and can be relied upon to invalidate CBM patents through the transitional program.

Ex Parte Reexamination: An Old Procedure Offering New Leverage For Third-Party Requesters – Without the Estoppel Risk

In most respects unchanged in the wake of the AIA, ex parte reexamination remains a viable option for asking the PTO to take a closer look at an issued patent without the risk of estoppel. Under this procedure, anyone can submit references for consideration by the Central Reexamination Unit. Available any time during the enforceability of a patent, ex parte reexamination is granted upon a finding that the submitted references raise a “substantial new question of patentability.” Notably, ex parte reexamination is not available to a third-party requestor if the PTO has already reached a final decision in a PGR or IPR that was requested by the same party (or its privies) on the same patent.

As in the past, prior art references remain limited to patents and printed publications. Post-AIA, however, third party requestors have a new tool in their arsenal – the explicit ability to submit statements that the patent owner made to a federal court or to the PTO concerning claim scope. This will help force patent owners to take consistent positions in each forum, and increase the odds that claims will be narrowed or invalidated in reexamination.

Table 4: Advantages and Disadvantages of Ex Parte Reexamination (Challenger’s Perspective)

 Advantages   Disadvantages 
  • Relatively low cost
  • Anonymity for requester
  • Good likelihood of file history clarification, and file history estoppel
  • No restriction on filing multiple requests or subsequent IPR
  • No estoppel risk in litigation
  • Potential stay of litigation 
  • Slow turnaround time (2+ years)
  • Low likelihood of complete success
  • Third-party requester cannot participate in or control proceedings after submitting references
  • Patent owner can add narrower claims to more specifically cover alleged infringers while avoiding prior art
  • Risk that patent owner will convince examiner of post-issuance, litigation-inspired claim construction arguments
  • Risk of “gold-plating” patent, especially if patentee makes available all prior art
  • No discovery 


Ex parte reexamination offers several significant advantages compared to other procedures. Significantly, a third-party requestor can remain anonymous, and faces no risk of estoppel in litigation based on references submitted. Initiating ex parte reexamination is often an effective strategy for staying litigation. The cost for an ex parte reexamination is relatively low (generally between $60,000 and $100,000). Moreover, there is no restriction on filing multiple subsequent ex parte reexamination requests. If an ex parte reexamination request is granted, it will likely yield some clarification of claim scope and create file history that will estop the patent owner from taking inconsistent positions in other venues. Recent PTO statistics show that 67% of ex parte reexamination proceedings result in claim changes (which is broadly defined to include the addition of new claims). This is nearly comparable to the 89% claim change rate for inter partes reexamination – the pre-AIA equivalent of inter partes review – at much lower cost.

The disadvantages of ex parte reexamination spring directly from its virtues. A third-party requestor may enjoy anonymity and the lack of estoppel, but cannot participate in and has no control over the proceedings once initiated. The tradeoff of lower cost is slower turnaround time (over two years) and no opportunity for discovery. Another disadvantage from the point of view of patent challengers is that interviews may be “off the record,” limiting the potential file history estoppel effect. A third-party requester runs the risk that reexamination will “gold plate” the patent – especially if the patent owner makes available all prior art – thereby giving the patent a stronger stamp of approval from the PTO that will be harder to challenge in court. Even worse for a would-be challenger, a patent owner can use reexamination as an opportunity to add narrower claims that will more specifically cover an allegedly infringing target while avoiding the prior art, or convince the examiner of post-issuance litigation-inspired claim constructions.

Derivation: A Limited Replacement for Interference Proceedings

Like IPR, PGR and the transitional program, derivation is available solely to a challenger, but unlike those review procedures and ex parte reexamination, the purpose of derivation is not merely to demonstrate the invalidity of the challenged claims. Instead, in a derivation proceeding, a challenger attempts to show that the patented invention was derived from the challenger’s own invention, which may or may not have been patented. This new procedure is necessary because, after the implementation of the FITF regime, first inventors will no longer be able to assert their rights through interference proceedings. Starting on March 16, 2013, and applicable to patent claims filed on or after that date, the only option a first inventor will have is a derivation proceeding – if a patent application has been filed on the purported first invention, and if the derivation petition is made within one year of the date of the first publication of the petitioner’s patent application. The petitioner in a derivation must show that the challenged application has a claim that is “the same or substantially the same” as at least one claim in its own application, that the challenged invention was derived from an inventor named in the petitioner’s application and that the inventor did not authorize the earlier filing.

Table 5: Advantages and Disadvantages of Derivation

 Advantages   Disadvantages 
  • Less expensive than court proceedings
  • Tribunal with specialized expertise in inventorship
  • Discovery available
  • Issues may be resolved through binding arbitration; proceedings may be terminated altogether by agreement on inventorship 
  • Examiner could reject previously allowed claims based on prior art
  • May still have to litigate infringement
  • PTO will likely wait to take any action until challenger’s claims are otherwise in condition for allowance 


Due to the adversarial nature of the proceeding, the $400 fee charged by the PTO will pale in comparison to the attorney’s fees that will be incurred through motion practice, interim hearings and discovery. Nonetheless, derivation proceedings are likely to prove less expensive than litigation. By analogy to the costs of interference proceedings reported in AIPLA’s 2011 survey, the total median cost for pursuing derivation, exclusive of appeals, may be around $340,000, depending on the number of claims involved, the technical complexity of the subject matter and the scope of discovery. Because derivations will be conducted by the PTAB, discovery will be governed by the general rules of that body. Thus, there will be mandatory initial disclosures, routine discovery (related to documents cited, or information inconsistent with positions advanced during the proceeding) and additional discovery by agreement of the parties or on motion if it meets the “interests of justice” standard. Parties will be able to resolve any issue by binding arbitration and may terminate the proceedings altogether upon reaching a settlement agreement as to correct inventorship.

It is likely that derivation proceedings will not be resolved quickly. By statute the PTO may defer action until three months after a patent is granted. The PTO has stated that it will generally wait to take action on a petition until the petitioner’s claim is otherwise in condition for allowance. Other disadvantages include the risk that, if not all claims covering a petitioner’s product are found to have been derived, the petitioner may still have to litigate infringement. In addition, claims of the petitioner could be invalidated in the course of the proceeding. The implementing rules provide that the PTAB will for good cause be able to authorize or direct the parties to address patentability issues that arise in the course of a derivation proceeding.

Recommendations for Patent Challengers

IPR can be a meaningful alternative to litigation if patents and publications available as prior art references clearly disclose the features of claims for which IPR is sought. The challenger preserves some grounds to show invalidity of the asserted claims in a subsequent proceeding, and by seeking to invalidate only some and not all claims in the patent all grounds may be preserved with respect to those unasserted claims. A finding of invalidity of some of the claims is beneficial in proving the invalidity of the unasserted claims in a later proceeding and if the patentee is forced to amend claims, the challenger can avoid past damages and may have a stronger non-infringement position.

As described above, as a practical matter PGR may not be available immediately after March 16, 2013, the date on which the FITF regime becomes effective. In seeking PGR (including review of CBM patents under the transitional program) it is beneficial to refrain from asserting invalidity of every claim so that grounds for invalidity are preserved with respect to at least the unasserted claims.

Ex parte reexamination is recommended for patent challengers who want to force patentees to take a position on a particular issue (e.g. claim construction) or prior art reference without running the risk of estoppel. It is also beneficial for third parties on a limited budget.
Derivation is recommended for third parties who have a strong case for prior invention and evidence that the challenged patent was derived from their own work without authorization.


The AIA also gives patent owners more options for putting their patents and file histories in better condition in preparation for enforcement. Between ex parte reexamination, supplemental examination and reissue, patent owners have the ability to address almost any omission, misrepresentation or other defect in an issued patent – without the risk of being thwarted by questions of subjective intent. Important features of these proceedings are summarized in Table B, and the advantages and disadvantages of each procedure are discussed below.

Ex Parte Reexamination: A Cost-Effective Option for Patent Owners to Preemptively Distinguish Prior Art

Ex parte reexamination is not just for patent challengers. Patent owners also frequently invoke this procedure to preemptively address specific prior art references that might be problematic in litigation. A patent that survives reexamination is more likely to withstand a validity challenge in court – as litigators are fond of reminding juries, a patent that has been reexamined has withstood the expert scrutiny of the PTO not once but twice.

Table 6: Advantages and Disadvantages of Ex Parte Reexamination (Patentee’s Perspective)

 Advantages   Disadvantages 
  • Relatively low cost
  • Can preemptively address problematic prior art in preparation for litigation
  • Ability to file formal statement and to schedule “off the record” interviews with examiner
  • Right of appeal 
  • Slow turnaround time (2+ years)
  • Risk that PTO will narrow or reject claims
  • Patent owner cannot terminate proceedings at will 


Patent owners have certain rights in ex parte reexamination proceedings that are not granted to third-party requestors. For example, patent owners have the power to influence the PTO’s views of the submitted references, by filing a statement setting forth the patent owner’s perspective on the references or arranging interviews with an examiner which may not be completely documented on the record. Patent owners, but not third parties, also have the ability to appeal an unfavorable decision.

The major risk for patent owners is that the PTO could find that a referenced patent or printed publication is prior art that necessitates amending or rejecting one or more claims of the patent. Moreover, despite the active role a patent owner can play in the proceedings, the patent owner cannot make the PTO terminate proceedings once initiated.

Supplemental Examination: A New Procedure to Immunize Patent Owners from Inequitable Conduct And Other Litigation Defenses

Patent owners interested in correcting information in an issued patent should consider requesting supplemental examination, a new procedure available exclusively to patent owners that applies to any enforceable patent, regardless of when it was issued. The request is judged according to the same “substantial new question of patentability” standard as ex parte reexamination, and will result in an ex parte reexamination if the PTO finds that any of the information presented raises a substantial new question of patentability. Under the AIA, the PTO is required to make its determination within three months after a request is filed. A supplemental examination is essentially conducted according to the same procedures as ex parte reexamination, except that the patent owner does not have the right to file a statement explaining its position.

Table 7: Advantages and Disadvantages of Supplemental Examination

 Advantages   Disadvantages 
  • No limit to the type of information that can be considered
  • Can change not only patents, but also other written information in the file history including declarations and Office Action responses
  • Inoculate against invalidity or unenforceability challenges in litigation
  • Not required to admit defect in patent
  • Submitted information remains in file history even if ex parte reexamination not granted 
  • Risk that examiner will reject previously allowed claims based on prior art
  • Must pay full fee for both supplemental examination and ex parte reexamination up front
  • Unlike ex parte reexamination, patent owner cannot file a statement
  • Only 12 items of information may be submitted
  • No amendments 


Supplemental examination offers many advantages for a patent owner. Notably, there is no limit to the type of information that can be corrected – the AIA merely specifies that the information must be in writing and must be “believed to be relevant to the patent.” Patent owners will therefore be able to use this procedure to make a wide variety of changes to their patent or file history, including to cure false statements or misrepresentations in the specification, declarations or responses to Office Actions. Unlike reissue, the patent owner is not required to admit the existence of a specific defect in the patent. Supplemental examination is expected to become a popular strategy for overcoming defects prior to enforcement. It can be used to inoculate against both invalidity and enforceability challenges – so long as unenforceability has not already been raised either as a defense in a lawsuit or in a Paragraph IV certification to the Food and Drug Administration. The AIA provides that a patent cannot be found unenforceable based on information “considered, reconsidered or corrected during a supplemental examination.” Supplemental examination can thus cure not only inequitable conduct, but also issues related to enablement, written description and patentable subject matter. Almost the only issue that cannot be cured is material fraud (a much narrower standard than inequitable conduct) – which, if found, may still result in cancellation of claims or a confidential referral to the U.S. Attorney General. Interestingly, the patent owner stands to benefit from this procedure even if the PTO does not order subsequent ex parte reexamination – because the submitted information will remain in the file history.

Among the disadvantages of supplemental examination is the risk that an examiner could reject previously issued claims based on prior art once the action has been opened. Another disadvantage is that the patent owner must pay both the supplemental examination fee of $5,140 and the ex parte reexamination fee of $16,120 up front, although the ex parte portion will be refunded if a substantial new question of patentability is not found. Patent owners are also forced to be judicious in their selection of references, in that only 12 items of information may be submitted with a request. Further, patent owners cannot file any amendments with their request.

Reissue: A Cost Effective Alternative to Supplemental Examination, Now Free of Subjective Restrictions

Reissue is another pre-AIA procedure that remains essentially the same, with one significant exception: a patent owner who seeks to correct defects in an issued patent is no longer limited to correcting defects that were made “without deceptive intent.” Similar to the addition of inequitable conduct immunity through supplemental examination, the aim of this change is to avoid the cost of adjudicating subjective questions. Through reissue, patent owners can address a range of defects relating to § 102 prior art, subject matter eligibility, utility, written description, enablement or clarity of the claims.

Table 8: Advantages and Disadvantages of Reissue

 Advantages   Disadvantages 
  • Cheaper than supplemental examination
  • Can narrow claims at any time, or broaden claims if filed within 2 years of original patent grant
  • No longer limited to fixing defects that arose without deceptive intent 
  • Patent owner must admit defect in patent
  • Slower than supplemental examination (average pendency just under 5 years) 


Reissue is cheaper than supplemental examination (even without an attendant ex parte reexamination) and gives the patentee the ability to change claim scope. Narrower claims can be added to reissues filed at any time. The scope of any claim can be broadened if a reissue request with at least one broadened claim is filed within two years of the original patent grant. In addition, if the reissue process is abandoned, the patent will retain its original claims (although the file history of the abandoned reissue application will remain publicly accessible). The main disadvantage of reissue is that – unlike with supplemental examination – a patent owner must admit the existence of a defect in its patent. Reissue is also slower than supplemental examination.

Recommendations for Patent Owners

Ex parte reexamination is recommended for patent owners who need to distinguish particular prior art prior to enforcement. Supplemental examination is recommended for patent owners seeking to immunize themselves against popular litigation defenses such as inequitable conduct prior to taking enforcement actions. Reissue is recommended for patent owners who wish to broaden claims, or who are seeking a cost-effective alternative to supplemental examination.

Certificate of Correction: The Cheapest Remedy for “Minor” Mistakes (Including Inventorship)

Patent owners may request a certificate of correction to fix three categories of mistakes: (i) mistakes by the applicant, (ii) mistakes by the PTO and (iii) mistakes concerning inventorship. For mistakes by the applicant, correctable errors are restricted to clerical or typographical mistakes, or mistakes “of minor character.” Mistakes are considered “minor” if they do not materially affect the scope of meaning of the patent. Accordingly, most mistakes affecting claim scope must be corrected by reissue rather than by a certificate of correction. Proposed corrections also cannot involve changes that would constitute new matter or require reexamination. In contrast to the AIA’s elimination of the subjective aspect of reissue proceedings, the AIA does not alter the restriction that only mistakes made in “good faith” may be corrected.

Patent owners may save time and money in litigation by preemptively addressing even errors that seem immediately apparent (such as obvious misspellings, or failure to perfect a claim for priority where other applications in the same family satisfy the statutory requirements). Requesting a certificate of correction is even more important where the existence or nature of an error is unclear (for example, “osmolality” mis-typed as “osmolarity”) because errors that are not evident from the face of the patent cannot be corrected in court and therefore may jeopardize patent validity in litigation.

Mistakes by the PTO can be addressed through a certificate of correction where such mistakes are “clearly disclosed” in the PTO’s records. The PTO has discretion in determining whether to issue a certificate of correction or a corrected patent, or to merely place the request in the file history. Although this procedure is not restricted to patent owners, the PTO has no obligation to act on or respond to submissions of information about mistakes in issued patents that are sent by third parties. Moreover, the PTO will not issue a certificate of correction without first affording a patent owner an opportunity to be heard.

Perhaps the most strategically significant correction that may be achieved through this procedure is correction of inventorship, which may either be requested through an application submitted to the Director of the Patent Office or sought through court action. Applications to the Director must be made by “all the parties and assignees” and must include “proof of the facts.” As with reissue, here too the AIA eliminates the requirement that errors have been made “without deceptive intent” on the part of the inventor to be added or removed. Errors in inventorship cannot invalidate a patent that has been corrected under this provision.

Table 9: Advantages and Disadvantages of a Certificate of Correction

 Advantages   Disadvantages
  • Cheapest option for correcting mistakes made by the applicant ($130 for errors in inventorship; $100 for other errors)
  • Correction of inventorship no longer limited to errors that arose without deceptive intent
  • Mistakes incurred through the fault of the PTO may be corrected for free 
  • Correction of mistakes by a patent owner are strictly limited to clerical or typographical mistakes, or mistakes of “minor character”
  • Cannot add new matter or make changes that would require reexamination
  • Only mistakes that the patent owner made in “good faith” may be corrected
  • The PTO retains discretion in determining whether and how to correct mistakes incurred through the fault of the PTO
  • Effect of corrections for mistakes other than inventorship is limited to later-arising causes of action and will not aid pending lawsuits 


Regardless of whether the mistake was made by the patent owner or by the PTO, a certificate of correction for mistakes other than inventorship becomes legally effective only for causes of action that arise after the certificate issues. Thus, the Federal Circuit has found that a certificate of correction issued while a lawsuit is pending cannot be given effect in that lawsuit.

Recommendations for Patent Owners

A certificate of correction is the most appropriate remedy for minor mistakes or mistakes that have clearly been incurred through the fault of the PTO. Where the desired change does not concern inventorship but nonetheless might have strategic significance, patent owners are advised to wait until a certificate of correction issues before filing suit.