Washington University School of Law, J.D.
  • cum laude; Dean's List
  • Washington University Law Review, Staff Editor
Yale University, B.S.
  • Biomedical Engineering


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Simeon Papacostas is an intellectual property attorney with substantial litigation experience in federal courts. He primarily focuses his practice on patent litigation in federal courts and post-grant proceedings before the patent office.  Simeon has argued matters in federal district court and before the Court of Appeals for the Federal Circuit and has represented clients in bench and jury trials as well as arbitrations in federal courts. He has represented clients across a wide range of industries, primarily dealing with medical devices, pharmaceuticals, biotechnology, and drilling and oilfield services, while also working with computer hardware and software, consumer products, and video games.

Simeon has additional experience dealing with patent-related antitrust issues, trademark litigation and counseling, and trade secrets, as well as general intellectual property due diligence and counseling regarding both domestic and international intellectual property matters.


Representative Matters

  • Represented a major pharmaceutical company in action brought against the USPTO under the Administrative Procedure Act regarding the proper calculation of patent term adjustment for client’s patent, arguing at both the district court and Federal Circuit; obtained the withdrawal of a holding of abandonment
  • Represented a major oilfield services company in its assertion of patents relating to marine seismic exploration technology against two major competitors; obtained summary judgment defeating counterclaims for inventorship, antitrust violations and unfair competition, and noninfringement of one defendant’s counterclaim as well as summary judgment of infringement of one of client’s patents; at trial in the Southern District of Texas, the team obtained a $106 million jury verdict and a finding by the jury that all four of the client’s patents were valid and willfully infringed
  • Represented a bus converter manufacturer in bench trial in the Eastern District of Texas
  • Represented a major biofuels manufacturer in multiple patent infringement litigations involving biobutanol technology
  • Represented a medical device manufacturer in patent infringement litigation involving hernia repair, chest wall reconstruction, and surgical wound repair devices
  • Represented a medical device manufacturer in patent infringement litigation involving laparascopic surgery port-site closure technology
  • Represented a medical device manufacturer in patent infringement litigation involving the engineering design and drug elution of cardiovascular stents

Prior Experience

  • Kirkland & Ellis LLP, Partner, 2014-2017; Associate, 2008-2014
  • U.S. House of Representatives, Legal Fellow, House Subcommittee on Courts, the Internet and Intellectual Property, 2008
  • Forest Pharmaceuticals, 2003-2005


  • Greek


Professional & Community Involvement

DuPage County Bar Association, IP Section, Chair, 2017-2018

Hellenic Bar Association, Scholarship Committee Member

Naperville Jaycees, Member


As pro bono of counsel to the International Association of Lawyers (“Union Internationale des Avocats”), filed amicus brief in human rights matter before the Inter-American Commission on Human Rights on the importance of maintaining an independent judiciary.

Advised various small businesses and individuals on a pro bono basis on trademark and copyright matters.