Three weeks after hearing a challenge to the heart of the Voting Rights Act, the Supreme Court will decide another important voting rights case following oral arguments today in Arizona v. The Inter Tribal Council of Arizona. In 2004, Arizona voters approved Proposition 200, a stringent anti-immigration law that included provisions requiring proof of citizenship to register to vote and government-issued photo ID to cast a ballot. Last year, the US Court of Appeals for the Ninth Circuit blocked the proof of citizenship requirement, which it said violated the 1993 National Voter Registration Act (NVRA). Under the NVRA, those using a federal form to register to vote must affirm, under penalty of perjury, that they are US citizens. Twenty-eight million people used that federal form to register to vote in 2008. Arizona’s law, the court concluded, violated the NVRA by requiring additional documentation, such as a driver’s license, birth certificate, passport or tribal forms. According to a 2006 study by the Brennan Center for Justice, at least 7 percent of eligible voters “do not have ready access to the documents needed to prove citizenship.”