HB 3856 establishes new requirements for law enforcement officers in Texas regarding immigration status verification and notification to federal authorities. It mandates that if a peace officer arrests or detains a person and determines that they are unlawfully present in the United States, the officer must notify U.S. Immigration and Customs Enforcement (ICE) or another federal agency within 12 hours. The bill also requires non-citizens who are legally present to carry federal immigration documentation and makes it a misdemeanor offense for failing to provide lawful immigration documents upon request or for providing false information about immigration status​.