William Pratt was a senior litigation partner in the New York office of Kirkland & Ellis. He practiced for 13 years in Kirkland's Chicago office before moving to New York in 1990 as one of the founding partners of the Firm's New York office — which now has in excess of 300 lawyers. William is a Fellow of the American College of Trial Lawyers. He acted as lead trial counsel on cases (both individual and class action) in a wide variety of substantive areas, including antitrust, securities, intellectual property, trade secrets, environmental, contract, and tort, and he had substantial experience before government regulatory agencies, including the Department of Justice, Federal Trade Commission and Securities and Exchange Commission, as well as various state agencies. William also had substantial experience counseling senior management and Boards of Directors on various litigation and other legal matters. He was lead counsel in both jury and bench trials in numerous state and federal venues throughout the United States, and he handled dozens of substantial arbitration matters in both the United States and overseas. He also handled cases on appeal in most of the federal appellate circuit courts, as well as in state appellate courts in New York, Illinois, California, and Texas.
In the 2014 edition of Chambers USA, America's Leading Lawyers for Business, William was well regarded for his commercial litigation experience. One client praised his "excellent trial skills and excellent technical understanding; very responsive and very attentive to detail." Previous editions recognized him as "an outstanding trial lawyer who is very skilled in developing strategies in complex cases" and noted his "superb courtroom presence" and "absolutely superb writing skills." William was recognized in the 2011–2023 editions of The Legal 500 United States as a "Leading Trial Lawyer." The Best Lawyers in America recognized William for his work in commercial litigation from 2007–2023 and antitrust litigation from 2011–2023. William has also been recognized as a “Litigation Star” by Benchmark Litigation from 2008–2024. The Legal 500 noted he has "built his reputation across a wide variety of substantive areas." He was also listed in the 2011–2014 editions of New York Super Lawyers.
