SB4, also known as the 2023 TX SB4, is a controversial bill in Texas that amends existing laws related to immigration enforcement and would make it a state misdemeanor to illegally cross the border from Mexico into Texas. It also increases the minimum sentence for smuggling immigrants and prohibits sanctuary cities in the state. The bill has been challenged in federal court by cities and counties and has been criticized for potentially leading to racial profiling. The bill was signed by Governor Abbott in May 2017 and it creates a new state crime for unauthorized entry into Texas, which is a class B misdemeanor on first offense.