John Schmidtlein has an active civil and criminal litigation practice, with a particular emphasis on antitrust litigation. Mr. Schmidtlein represents corporations, both as defendants and plaintiffs, in a variety of antitrust suits, and also represents corporations and individual corporate officers in grand jury investigations. He is currently lead counsel in numerous antitrust class action lawsuits pending in federal and state courts throughout the United States. He has represented clients in many of the most significant antitrust cases of the 1990s and today, including In re Vitamins Antitrust Litigation, In re High Fructose Corn Syrup Antitrust Litigation, In re Lysine Antitrust Litigation, In re Citric Acid Antitrust Litigation, In re MSG Antitrust Litigation, In re Graphite Electrodes Antitrust Litigation, and In re Magazine Publishers Antitrust Litigation. He also was actively involved in the firm's representation of the nine non-settling States who litigated the closely followed Microsoft antitrust case, State of New York, et al. v. Microsoft Corporation.

Mr. Schmidtlein also is involved in the firm's sports law practice. He has represented both sports teams and individuals in antitrust matters arising in the professional sports context. He has taught Sports Law at the Georgetown University Law Center and George Washington University Law School.