Justin L. Krieger
Partner

1400 Wewatta Street Suite 600, Denver, CO USA 80202

701 Pennsylvania Avenue, NW Suite 200, Washington, DC USA 20004

Overview

Justin Krieger is a first-chair PTAB litigator and the Managing Partner of Kilpatrick’s Denver office. He has led dozens of PTAB proceedings for both petitioners and patent owners, achieving a success rate of over 90%— making him one of the most effective PTAB advocates in the country. His work has earned him repeated recognition: Law Week Colorado named him Barrister’s Best IP Litigator in 2021 and 2024; Managing IP nominated him for PTAB Practitioner of the Year in 2025; and he is ranked by Chambers USA, LawDragon 500, and IAM 1000 as a leading IP practitioner. In addition to his PTAB practice, Justin handles district court and ITC litigation, client counseling, and patent prosecution across a range of technical fields, including chemistry, oil and gas, mechanical systems, and medical devices. He chairs the American Chemical Society’s Committee on Intellectual Property and teaches PTAB litigation as an adjunct professor at the University of Denver Sturm College of Law.

Justin lectures and publishes frequently on various intellectual property topics, including the America Invents Act, the “on sale” bar to patentability, IPR and PGR proceedings, best practices in drafting patent applications and the Defend Trade Secrets Act of 2016.

Justin was recognized in 2024 and 2025 by The Best Lawyers in America® for Patent Law. He was recommended by Legal 500 US in 2018, 2020, 2021, 2024 and 2025 for Patent Prosecution. Justin was named a top national patent practitioner in 2025 and the seven years immediately preceding by IAM Patent 1000 – The World's Leading Patent Practitioners. He was recognized as an “IP Star” in 2025 and the three years immediately preceding by Managing Intellectual Property magazine. Justin is listed in the 2025 edition of Chambers USA: America’s Leading Lawyers for Business in the area of Intellectual Property. In 2021 and 2024, he was listed in Barrister's Best and selected as the “People’s Choice” Best IP Litigator by Law Week Colorado.

While attending law school, Justin was a member of the Florida Law Review.

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Experience

Justin supervises a post-grant patent practice team that has consistently obtained favorable results for the firm’s clients. He has served as lead counsel in well over 20 IPR and PGR proceedings, representing clients both as petitioner and patent owner. Justin has repeatedly beaten the odds: representing Patent Owners, he successfully achieved denial of institution in 8 IPRs, and won 5 IPRs after trial. All five cases going to trial resulted in the validation of all instituted claims—a result achieved in fewer than 5% of IPR proceedings. Representing client TerraLithium LLC, in 2020-2021, Justin achieved complete victories in 7 IPRs, with institution denied or all patent claims affirmed after trial for all 7 different patents.

Representing Petitioners, Justin has been equally successful: In 2017, Justin successfully represented Petitioner in two IPRs, resulting in the Patent Owner requesting adverse judgment. In 2018, Justin successfully took three IPRs to trial on behalf of Petitioner. In 2019, he achieved another win as IPR petitioner, resulting in an early grant of a client’s motion to terminate the proceeding on terms highly favorable for the client.

Justin also actively prepares non-infringement and validity opinions including comprehensive freedom-to-operate (FTO) analyses in the chemical, polymer, medical device, and mechanical arts from both due diligence and litigation perspectives. Justin also has been actively involved in numerous patent litigation matters and has participated in all phases of discovery, claim construction (Markman hearings), trial, and appeals. He is also experienced in Section 337 investigations before the U.S. International Trade Commission (ITC).

Justin leads a patent prosecution team for clients in the fields of industrial chemistry and chemical engineering, pharmaceuticals, agrochemicals, medical devices and analytical instruments.

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Insights

Blogs

Post Grant Proceedings

The PREVAIL Act: One Step Closer to Passage

Post Grant Proceedings

Director Vidal Orders Rehearing on Adverse Judgment

Post Grant Proceedings

The Latest on Petitioner Estoppel

Post Grant Proceedings

Recent Rulings on IPR Estoppel

Education

University of Florida College of Law J.D. (1999)

College of William and Mary B.S. (1995) Chemistry

Admissions

Colorado (2018)

District of Columbia (2002)

New York (2000)

Court Admissions

U.S. Court of Appeals for the Federal Circuit

U.S. District Court for the District of Columbia

U.S. District Court for the Eastern District of Virginia

U.S. Patent and Trademark Office

U.S. Supreme Court

Professional & Community Activities

University of Denver Sturm College of Law, Adjunct Professor of Law, PTAB Practice

Board Member, Colorado IP American Inn of Court

Law360, Colorado Editorial Advisory Board (2024-2025)

Chair, American Chemical Society (ACS) Committee on Patents and Related Matters

Chair-Elect, American Chemical Society (ACS), Colorado Section

Board of Trustees, ACS Division of Chemical Education (2020-2022)

PTAB Bar Association

Federal Circuit Bar Association (member, PTAB & TTAB Committee)

American Bar Association

American Intellectual Property Law Association

Intellectual Property Owners Association

ITC Trial Lawyers Association

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