The Supreme Court announced today that it will hear a critical voting rights case next year. Arizona has appealed a 9th Circuit decision that barred the state from requiring proof of citizenship from those registering to vote via a federally-approved registration form. Current federal law allows voters to register via federal form instead of a state-specific form. Those opting to do so must swear under penalty of perjury that they are citizens. Arizona’s law, which is currently stayed, would require voters using that form to jump over an extra hurdle to register, requiring them to show proof of their citizenship, a provision disproportionately affecting low-income and minority voters.

The AP explains:

The ruling applies only to people who seek to register using the federal mail-in form. Arizona has its own form and an online system to register when renewing a driver’s license. The court ruling did not affect proof of citizenship requirements using the state forms.

Arizona officials have said most people use those methods and the state form is what county officials give people to use to register. But voting rights advocates had hoped the 9th Circuit decision would make the federal mail-in card more popular because it’s more convenient than mailing in a state form with a photocopy of proof of citizenship.

The mail-in card is particularly useful for voter registration drives, said Robert Kengle of the Lawyers’ Committee for Civil Rights Under Law, which is representing Native American and Hispanic groups in the case.

The conservative wing of the Supreme Court has been eager to challenge voting rights laws in recent years. In 2008, a 6-3 majority of the court upheld Indiana’s voter ID law, paving the way for suppressive voter ID measures throughout the country. The Court may also hear a challenge to section 5 of the Voting Rights Act, which requires federal preclearance for voting rights changes in states and counties with a history of discrimination at the ballot box. Successful court challenges to discriminatory voting law changes this year have shown just how essential that provision still is.

While the composition of the Supreme Court is unlikely to change before these cases are heard, they underscore the importance of federal courts in this election. Not only are federal courts the final protection we have against discriminatory voter suppression laws, the makeup of these courts is on the line in the presidential election. Either Mitt Romney or President Obama could pick up to three Supreme Court Justices and dozens of federal court judges in the next term. Romney has promised to appoint Justices like Antonin Scalia and Clarence Thomas, who have both signaled their hostility to voting rights. If he does, and the Court shifts farther to the right, we could see decades of progress for fair and free elections slip away.