This bill, titled the "Stop Dangerous Sanctuary Cities Act," seeks to strengthen the ability of state and local law enforcement to cooperate with federal officials in addressing individuals illegally present in the United States, particularly those identified as violent criminals or suspected terrorists. It establishes provisions to facilitate this cooperation and impose consequences on jurisdictions that do not comply. A key provision states that any state or local entity complying with a Department of Homeland Security (DHS) detainer will be deemed an agent of DHS and granted the same authority as DHS officers for actions taken under the detainer. Furthermore, it provides significant legal protection: in any legal challenge against a state or local entity for complying with a detainer, no liability will lie against the jurisdiction, and the United States government will be substituted as the defendant for the officer or employee involved. However, this protection does not extend to individuals who knowingly violate civil or constitutional rights. The bill defines a "sanctuary jurisdiction" as any state or political subdivision with a policy that prohibits or restricts sharing immigration status information with federal entities or complying with lawful DHS detainer requests. An exception is made for policies that solely protect victims or witnesses of criminal offenses. This definition is crucial for determining eligibility for federal funding. To enforce compliance, the bill makes sanctuary jurisdictions ineligible for various federal funding programs. Specifically, it amends existing law to prevent such jurisdictions from receiving grants from the Economic Development Administration and Community Development Block Grants . If a jurisdiction becomes a sanctuary while receiving Community Development Block Grants, it will be required to return the funds, which will then be reallocated to non-sanctuary jurisdictions. These financial penalties are set to take effect on October 1, 2025.