The Supreme Court is letting stand a lower court's ruling barring Florida from enforcing a contentious immigration law that imposes criminal penalties against undocumented migrants who enter the state.

The law, enacted this year, made it a crime for unauthorized migrants to enter the state. Challengers say immigration is a federal matter.

At least seven states, including Texas, Oklahoma and Iowa, have passed similar laws in recent years. All are blocked for now or have not yet taken effect.