The Supreme Court will take up an appeal from Arizona over its requirement that people prove they are American citizens before registering to vote.
The justices on Monday said they will review lower federal court rulings that blocked the law.
Those courts said that federal law trumps the Arizona requirement. Federal law allows voters to fill out a mail-in voter registration card and swear they are citizens under penalty of perjury, but it doesn't require them to show proof as Arizona's 2004 law does.
Gov. Jan Brewer championed passage of the law via an initiative known as Proposition 200 when she was secretary of state.
The law has been through a host of challenges and appeals in the federal court system for the last seven years.