Named as one of Law360’s 2021 Appellate Rising Stars, David Zimmer is a partner in the firm’s Litigation Department, and a member of its Appellate Litigation practice. Mr. Zimmer focuses on U.S. Supreme Court and appellate matters and complex commercial litigation, and has litigation experience in a wide range of areas, with a particular focus on intellectual property, administrative law, and consumer financial services. He has argued three cases before the U.S. Supreme Court, and has briefed and argued other appeals and dispositive motions in federal and state courts across the country. Mr. Zimmer maintains an active pro bono practice, focused primarily on immigration issues, for which he was awarded Goodwin’s Robert B. Fraser Pro Bono Award. Mr. Zimmer is ranked in Chambers USA: America’s Leading Lawyers for Business as an “Up and Coming” attorney in the Nationwide Appellate Rankings, which identified his “notable strength in immigration and patent infringement-related disputes.”  His advocacy has also been recognized by Law360, The Financial Times, The American Lawyer, Managing IP, Massachusetts Lawyers Weekly, the American Immigration Lawyers Association, and the Legal Aid Society.

Prior to joining Goodwin, Mr. Zimmer clerked for Justice Elena Kagan of the U.S. Supreme Court and Judge William A. Fletcher of the U.S. Court of Appeals for the Ninth Circuit. In addition to his work at Goodwin, Mr. Zimmer serves as a Lecturer at Harvard Law School, where he directs the Federal Courts Clinic and teaches the Federal Courts Clinical Seminar. He also serves on the Board of Directors for both the ACLU of Massachusetts and Lawyers for Civil Rights.





Mr. Zimmer’s recent U.S. Supreme Court representations include the following:

  • Mr. Zimmer successfully argued two of the most important immigration cases the Supreme Court has decided in recent years, both concerning eligibility for cancellation of removal. A noncitizen must have a specific period of permanent residence or continuous presence in the country to be eligible for cancellation. The stop-time rule bars a noncitizen from accruing additional time when the government serves “a notice to appear,” which the government must serve to initiate removal proceedings. In Pereira v. Sessions, 138 S. Ct. 2105 (2018), the Supreme Court reversed the decisions of six courts of appeals and held, by an 8-1 vote, that the government must comply with the statute’s definition of a notice to appear to trigger the stop-time rule. In Niz-Chavez v. Garland, __ S. Ct. __ (Apr. 29, 2021), the Supreme Court resolved an interpretive question left open by Pereira and held that a notice to appear is a specific notice document, not a collection of information the government can divide up however it wants. These two cases significantly expanded access to cancellation of removal, allowing thousands of noncitizens to apply to remain in this country with their families. The American Immigration Lawyers Association awarded Mr. Zimmer and his team with the Jack Wasserman Memorial Award for Excellence in Litigation based on their work on Pereira. Mr. Zimmer’s work on Pereira was also recognized by The Financial Times in its 2019 North America Innovative Lawyers Report.
  • On behalf of an asylum applicant, Mr. Zimmer presented oral argument before the Supreme Court in Garland v. Dai, a case concerning the principles a federal court of appeals should apply when reviewing an agency decision that denies an asylum application without finding that the applicant’s testimony lacked credibility. The Supreme Court agreed with our argument that a court of appeals cannot uphold the agency’s denial of asylum by making an adverse credibility determination that the agency did not make itself. The Court held, however, that the court of appeals had not adequately considered whether the agency might have permissibly denied our client asylum without making an explicit adverse credibility finding. The Court therefore remanded for further proceedings. 
  • Representing a generic pharmaceutical company seeking to launch a generic version of a anti-nausea drug used by chemotherapy patients, Mr. Zimmer co-authored the brief and served as second chair in the first Supreme Court case to consider the revised standards for patentability under the 2011 America Invents Act. The Court unanimously agreed with our client’s argument that an invention is “on sale” for purposes of the statute if it is sold or offered for sale, and that it does not matter whether the sales are public or make the invention “available to the public” more broadly. Helsinn Healthcare S.A. v. Teva Pharm. USA, Inc., 139 S. Ct. 628 (2019).
  • On behalf of a major banking client, Mr. Zimmer co-authored the petition for certiorari and merits briefs that persuaded the Supreme Court to grant certiorari to resolve questions about the scope of the Fair Housing Act, adopt our client’s argument, and set aside the appellate decision applying a relaxed causation standard.

Mr. Zimmer’s other significant representations include the following:

  • Mr. Zimmer presented oral argument and drafted briefs that successfully convinced the First Circuit to hold that our client’s sustained overdraft fees do not qualify as “interest” under regulations implementing the National Bank Act. The court’s decision was the first appellate decision addressing the proper classification of sustained overdraft fees. Fawcett v. Citizens Bank, N.A., 919 F.3d 133 (1st Cir. 2019).
  • Massachusetts Attorney General Maura Healey appointed Mr. Zimmer to serve as Special Assistant Attorney General in order to represent District Attorneys Marian Ryan and Rachael Rollins in their ongoing challenge to ICE’s policy of conducting civil immigration arrests at Massachusetts state courthouses. The litigation strategy Mr. Zimmer developed has been successfully implemented in multiple cases pending across the country. In 2019, The American Lawyer recognized Mr. Zimmer as a Litigator of the Week nominee for his groundbreaking work on this case.
  • Mr. Zimmer is representing Actavis in New York state court in a commercial dispute concerning a license and supply agreement. Mr. Zimmer successfully briefed and argued a partial motion for summary judgment significantly limiting damages and then defended that win on appeal. Shionogi Inc. v. Actavis Labs, LLC, 187 A.D.3d 422 (1st Dep’t 2020).
  • Representing the company that makes Invisalign, Mr. Zimmer developed appellate strategy and co-authored briefs that convinced the Federal Circuit to vacate the PTAB’s decision finding our client’s patent invalid. Align Technology, Inc. v. ClearCorrect Operating, LLC, 745 Fed. Appx. 361 (Fed. Cir. 2018).
  • Mr. Zimmer developed appellate strategy and co-authored briefs that convinced the Federal Circuit to reverse the district court’s factual findings as clearly erroneous, and hold that the patent asserted against our client was invalid as obvious. The Federal Circuit’s decision cleared the path for our client to launch its generic pharmaceutical product. Bayer Pharma AG v. Watson Laboratories, Inc., 874 F.3d 1316 (Fed. Cir. 2017).
  • Mr. Zimmer co-authored winning briefs in a significant appeal in the Federal Circuit about the scope of “covered business method” review of patents by the Patent Trial and Appeal Board. Managing IP named the case one of 2016’s “Milestone Cases.” Unwired Planet, LLC v. Google Inc., 841 F.3d 1376 (Fed. Cir. 2016).
  • On behalf of a major mortgage lender, Mr. Zimmer co-authored briefs persuading a California trial judge to grant judgment notwithstanding the verdict on a multimillion-dollar tort judgment against our client, and appellate briefs persuading the California Court of Appeal to affirm the trial court’s decision and the California Supreme Court to deny review.
  • Mr. Zimmer has successfully briefed and argued cases before the Second and Ninth Circuits on behalf of pro bono clients, convincing the courts to grant petitions for review from decisions of the Board of Immigration Appeals finding our clients removable. He has also played a leading role in dozens of other petitions for review in immigration cases. In recognition of this work, the Legal Aid Society awarded Mr. Zimmer its Pro Bono Publico Award.
Professional Activities

In addition to his work at Goodwin, Mr. Zimmer currently serves as a Lecturer at Harvard Law School and as the Director of its Federal Courts Clinic. He also serves on the Board of Directors for both the ACLU of Massachusetts and Lawyers for Civil Rights; is a member of the Emerging Leaders Council of the Legal Services Corporation; and is on the Amicus Committees of the Boston Bar Association and the American Immigration Lawyers Association.

Prior to joining Goodwin, Mr. Zimmer served as a law clerk to Justice Elena Kagan of the Supreme Court of the United States, and Judge William A. Fletcher of the U.S. Court of Appeals for the Ninth Circuit. He also previously worked as an associate at Keker, Van Nest and Peters.


Mr. Zimmer is recognized in Chambers USA as “Up and Coming” in  Nationwide Appellate Litigation. Clients praise him for “[thinking] issues through and [making] sure to look round corners.”

Mr. Zimmer was a recommended lawyer for Appellate by The Legal 500 in 2021 and 2022. While attending law school, Mr. Zimmer was an Articles Editor and the Forum Chair for the Harvard Law Review.

In 2021 and 2022, Benchmark Litigation selected Mr. Zimmer for their 40 & Under Hot List.

In The News









J.D., 2010
Harvard Law School
(magna cum laude)
M.P.A/I.D., 2010
Harvard Kennedy School of Government
B.A., 2004
Harvard College
(magna cum laude)


2012 to 2013 U.S. Supreme Court, Honorable Elena Kagan
2010 to 2011 U.S. Court of Appeals for the Ninth Circuit, Honorable William A. Fletcher





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U.S. Court of Appeals for the District of Columbia Circuit
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U.S. Court of Appeals for the Federal Circuit
U.S. District Court for the Northern District of California
U.S. District Court for the Central District of California
U.S. District Court for the District of Massachusetts
U.S. Court of Federal Claims
U.S. Tax Court
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