This legislation, titled the "GATE CRASHERS Act," aims to amend title 18 of the United States Code by creating a new criminal offense for unauthorized access to Department of Defense facilities. Specifically, it makes it unlawful for any individual to go upon property under the jurisdiction of the Department of Defense that has been clearly marked as closed or restricted, without proper authorization. The bill establishes a tiered penalty structure for violations. A first offense can result in a fine, imprisonment for up to 180 days, or both. For a second offense, penalties increase to a fine, imprisonment for up to 3 years, or both, while a third or subsequent offense carries a fine, imprisonment for up to 10 years, or both.