From victories in the Supreme Court of the United States to precedent-setting wins in criminal procedure, Williams & Connolly lawyers regularly argue in appellate courts nationwide.  The firm's ranks include over eighteen Supreme Court clerks, and former clerks from all thirteen of the federal courts of appeals. Thirteen attorneys currently practicing at the firm have argued before the Supreme Court, and seven have argued there multiple times. The extensive trial practice of the firm's lawyers gives them the unusual ability to appreciate how best to present trial-related issues on appeal.

The firm successfully represented MedImmune, Inc. in the Supreme Court, which by an 8-1 vote reversed the Federal Circuit and reinstated MedImmune's lawsuit seeking invalidation of a Genentech biotechnology patent.  The firm's representation of Richard Grasso (former chairman and chief executive officer of the New York Stock Exchange) in a challenge to his compensation ended with successful appeals before the New York Court of Appeals and the Appellate Division effectively dismissing the Attorney General's claims.  The Wall Street Journal described it as "one of the biggest defeats suffered by authorities in the past decade in white-collar civil and criminal cases aimed at financial improprieties." 

The firm successfully argued in the First Circuit Court of Appeals for the reversal of the conviction of a Republican party official for election day campaign activity. Recently in the Sixth Circuit Court of Appeals, Williams & Connolly lawyers  successfully argued that the government, in conducting a grand jury investigation, could not use a "taint team" of government prosecutors to conduct a privilege review of subpoenaed documents in a third party's possession, as to which subjects of the grand jury investigation claimed a privilege.  This was a case of first impression in the federal appellate courts.  Williams & Connolly lawyers also prevailed in the Eighth Circuit on an attorney-client privilege issue arising out of a federal grand jury subpoena, and in the Federal Circuit in a patent infringement case over extracellular matrices used to treat burn victims and injured soldiers.  The firm also upheld its trial win in the Seventh Circuit Court of Appeals in an ERISA challenge to the pension plan of a Midwestern power company.  In addition to its extensive practice in virtually every imaginable kind of case in federal and state appellate courts throughout the country, the firm also has an active appellate pro bono practice through its relationship with the Maryland Public Defender's Office. (See Pro Bono).