A controversial Texas law that is the focus of an intense legal battle could soon become one of the toughest immigration measures in the country. Hours after the U.S. Supreme Court kept the policy in play, a federal appeals court blocked it Tuesday.

The policy allows law enforcement in Texas to arrest immigrants illegally crossing from Mexico. Although it’s on hold for now, some are putting out a warning to any New Mexican traveling to Texas.

The ACLU’s main concern is the possibility of racial profiling and discrimination against people of color who are in the country legally. The ACLU and Las Americas are suing the state of Texas, saying the law is blatantly unconstitutional.

“Immigration is not just historically a federal government issue but is constitutionally a federal government priority. Local police are not trained in immigration at all, they don’t go through the same type of academy that border patrol does or that Immigration and Customs Enforcement officers do,” said Leonardo Castañeda, a border and immigration policy advocate at the ACLU of New Mexico.

While the law is not in effect at this moment, ACLU officials say they have heard concerns already from New Mexicans. They say Texas law enforcement officers have already become aggressive in questioning people’s immigration status when they are going to Texas to visit family, go to the hospital, or even go back to college.

So the ACLU is reupping their travel advisory for folks going to Texas and encouraging them to take necessary precautions.

“Make sure you have any relevant immigration documentation, make sure your family members are contacted if you are going to Texas so there are steps in place if anything does happen,” Castañeda said.