The American Civil Liberties Union has issued a "travel alert" for Texas Tuesday following the passage of Senate Bill 4, the so-called "sanctuary cities" bill, into law.

SB4 requires law enforcement agencies across the state to honor U.S. Immigration and Customs enforcement detainers. They're requests to hold someone in jail while their immigration status is checked out. Gov. Greg Abbott signed SB4 into law during a Facebook Live video Sunday evening.

The "travel alert" informs anyone planning to travel to Texas in the near future to anticipate the possible violation of their constitutional rights when stopped by law enforcement.

"The law gives a green light to police officers in the state to investigate a person’s immigration status during a routine traffic stop, leading to widespread racial profiling, baseless scrutiny, and illegal arrests of citizens and non-citizens alike presumed to be “foreign” based on how they look or sound," the ACLU said in a statement.

The ACLU's travel alert "applies to all travelers to Texas, including U.S. travelers from other states and U.S. citizens."