The Refuge System Protection Act of 2023 authorizes the U.S. Fish and Wildlife Service to pursue legal claims against individuals, entities, or equipment that damage wildlife refuges, fish hatcheries, and other federally managed lands and waters. The Attorney General can file civil lawsuits or property claims to recover response costs (expenses to prevent or minimize damage) and damages (compensation for lost, destroyed, or injured resources) from those responsible for harming protected lands, wildlife, archaeological sites, and cultural resources. The law includes several legal defenses, such as when damage results from lawful activities, acts of God, acts of war, or necessary self-defense, and establishes a $5,000 minimum threshold for claims to avoid litigation over minor injuries. Money recovered through settlements or court awards goes into a dedicated Fish and Wildlife Service fund used only for restoring damaged resources, assessing harm, or acquiring equivalent replacement resources at the affected refuge or facility. The bill allows the Secretary of the Interior to also accept monetary donations for response efforts and clarifies that Alaska's special land management laws take priority if they conflict with this legislation.