Congress has broad authority pursuant to the Commerce Clause to enact laws in areas that may overlap with traditional state jurisdiction. As such, Congress has passed complex statutory provisions that regulate the possession, receipt, transfer, and manufacture of firearms and ammunition. Generally, courts have upheld the validity of firearms laws pursuant to Congress's commerce power. However, courts have been confronted with the question of whether federal laws can be applied to intrastate possession and intrastate transfers of firearms, or whether such application exceeds the authority of Congress. This book explores these cases and how courts have analysed these as-applied challenges under the Supreme Court's Commerce Clause jurisprudence primarily set forth in United States v. Lopez.