The U.S. Supreme Court agreed to hear a case that focuses on the role of states in prosecuting immigrants for using illegal Social Security numbers.

The grant isn’t a surprise given that U.S. Solicitor General Noel Francisco told the justices in December they should hear the case. The court frequently follows the solicitor general’s recommendation.

Identity theft is a nationwide problem that affected some “17.6 million people, or 7 percent of all U.S. residents age 16 or older,” Kansas told the justices in urging them to take the case.

If the court refused to hear the case, the federal government...