A Practice Note discussing the antitrust issues that arise in patent pools and cross-licenses. The Note focuses on the potential procompetitive benefits and anticompetitive harms of patent pools, including those relating to patent thickets, patent-holdups, and royalty stacking, the relevant antitrust laws, the applicable legal standards, including the factors the courts and agencies consider most relevant, and guidance from the Federal Trade Commission (FTC) and the Antitrust Division of the Department of Justice (DOJ).