William A. Streff, Jr. was a partner in the Chicago office of Kirkland & Ellis. He concentrated in intellectual property litigation, transactions (including international strategic alliances) and counseling. He represented companies involved in the litigation, acquisition, development and licensing of computer hardware, firmware, software and systems; semiconductor processing technology; semiconductor circuitry, including DRAM's and MPU's; telecommunications, networks, satellite and cable communications systems; high definition and satellite television systems, digitally controlled fuel systems and related products and services.

He received a Bachelor of Science Degree in Mechanical Engineering and Astronautical Sciences from Northwestern University and graduated cum laude from the Northwestern University School of Law. During engineering and law school he programmed mainframe computers specializing in law related and university related computer applications.

He is a registered patent attorney, a member of the bar of the Court of Appeals for the Federal Circuit, the Court of International Trade and numerous Federal District Courts and Courts of Appeals. He is a member of the American Bar Association, including sections on litigation, antitrust and intellectual property.

He was an Adjunct Professor at the Northwestern University School of Law, teaching the Intellectual Property Course and the International Intellectual Property Seminar (with Professors D'Amato and Long); an Adjunct Professor at the Chicago-Kent College of Law, teaching the Patent Trial Advocacy Course; and served on the faculty of The John Marshall Law School, teaching the Intellectual Property Law Master Class, "Effective Advocacy for Itellectual Property Attorneys."

He presented numerous seminars on various aspects of intellectual property, antitrust and computer law and technology to executives, lawyers and law students in the U.S., Tokyo and Seoul. He has written articles for The National Law Journal and for Legal Times on computer-based evidence and has lectured on intellectual property related topics for the Illinois Institute for Continuing Legal Education, the Tokyo Japanese bar associations, the Promotion Marketing Association, the Texas Institute of Continuing Legal Education, PricewaterhouseCoopers Legal Tech and PricewaterhouseCoopers General Counsel Forum, Northwestern University School of Law Corporate Counsel Institute, the American Conference Institute, and The Korea-U.S. Science Cooperation Center.

Described as "a go-to guy for litigation," "confident" and "a phenomenal trial lawyer with a long track record," clients say that they "would not hesitate to recommend a case to him," according to Chambers USA, America's Leading Lawyers for Business. William has been selected as a leading IP attorney in every guide from 20032018. He was listed in The Best Lawyers in America in the areas of Litigation - Intellectual Property and Patents 2007–2019. In addition, he was named the Best Lawyers' 2015 Chicago Litigation – Patent "Lawyer of the Year", an honor only a single attorney is awarded in each practice area in each community. William was named as a 2013 Client Service All-Star and as a 2015 Client Service All-Star by The BTI Consulting Group Inc. He has been named an "Illinois Super Lawyer" every year from 2005 to 2019. In 2012, he was selected to The International Who's Who of Patent Lawyers. He was also selected as a "2013 Top Rated Lawyer in Intellectual Property," by American Lawyer Media and Matindale-Hubbell.

William's role in Kirkland's annual Computer Technology and the Practice of Law seminar was mentioned in the articles, Y2K Advice From Kirkland & Ellis, and The Road Warriors. He also was profiled by IP Worldwide in the article, Big House on the Prairie. The Wall Street Journal covered his patent infringement win for client, Kubota Corporation, in the article, Jury Strikes Down Deere's Patent Claim Against Kubota Corp. William's representation of Kubota Corporation was also chosen as one of the top 20 defense wins in 2002 by The National Law Journal. In addition, his representation of Kubota Corporation was mentioned in the IP Law & Business, Long-Term Sluggers article, a feature on Kirkland's IP practice, as part of the first IP Litigation Department of the Year survey. 2004 IP Litigation Department of the Year contest, in which Kirkland was a finalist. William is also mentioned in the article, Kirkland & Ellis LLP Represents Kubota Corp. in Major Patent Lawsuit Victory Over Deere & Co.


Thought Leadership


Organizer, Moderator and Presenter: Kirkland & Ellis LLP, “Annual Technology and the Law Seminar,” 1994–present

Assistant Guest Professor, "United States Patent Litigation" course, Tokai University School of Law, 2006


Selected for inclusion in Who’s Who Legal: Patents 2016


Admissions & Qualifications

  • 1974, Illinois
  • Registered to practice before the United States Patent and Trademark Office


  • Supreme Court of the United States
  • Supreme Court of Illinois
  • United States Court of Appeals for the Federal Circuit
  • United States Court of Appeals for the Third Circuit
  • United States Court of Appeals for the Seventh Circuit
  • United States Court of Appeals for the Ninth Circuit
  • United States Court of International Trade
  • United States District Court for the Northern District of Illinois
  • United States District Court for the Northern District of California
  • United States District Court for the Northern District of New York


  • Northwestern Pritzker School of LawJ.D.cum laude1974
  • Northwestern UniversityB.S.M.E.A.S.1971