To amend title 18, United States Code, to provide penalties for certain obstructions of the enforcement of Federal immigration laws, and for other purposes.

Stopping Lawless Actions of Politicians Act of 2018 or the SLAP Act of 2018 This bill amends the federal criminal code to make it a crime for a state or local official to knowingly release from custody an individual who is an alien subject to a detainer. It imposes criminal penalties—a fine, a prison term of up to five years, or both—on a violator. A state or political subdivision that complies with a detainer is deemed to be an agent of the Department of Homeland Security and is authorized to take actions to comply with the detainer. The bill limits the liability of a state or political subdivision, or an officer or employee of such state or political subdivision, for actions in compliance with the detainer.