The U.S. Department of Justice will sue Iowa to block a new immigration law criminalizing “illegal reentry” if it remains in effect, a top DOJ official wrote to Gov. Kim Reynolds and Attorney General Brenna Bird Thursday. In a letter obtained by the Des Moines Register, Principal Deputy Assistant Attorney General Brian Boynton wrote that the department “intends to bring a lawsuit to enforce the supremacy of federal law and to enjoin” the new immigration law passed as Senate File 2340. The law, signed in April after passing the Republican-led Legislature, allows Iowa officers to arrest undocumented immigrants who have previously been deported or barred from entering the country. If convicted, a judge could order that they be deported back to their home country.