DES MOINES, Iowa (AP) — The Trump administration on Friday moved to dismiss lawsuits against Iowa and Oklahoma brought by the Biden administration’s Department of Justice, which challenged the states’ immigration laws making it a crime for someone to be in the state if they are in the U.S. illegally.

White House press secretary Karoline Leavitt cited the Immigration and Nationality Act of 1952 on Tuesday to explain the arrest and planned deportation of a Palestinian activist and legal U.S. resident with a green card.

The act comes up so frequently because it is the legal foundation of modern immigration law, encompassing a vast range of regulations and procedures.