The case involves different legal issues than the Voting Rights Act case, which was about voter discrimination. The central argument of this case is not that the Arizona law is discriminatory -- it received preclearance under the Voting Rights Act -- but that it creates unlawful obstacles to registering people to vote. The 9th Circuit Court of Appeals has ruled against Arizona, saying the NVRA preempts the proof-of-citizenship part of the state's law.
The outcome of the case could have implications beyond Arizona. If the Supreme Court rules that the state violated federal requirements, then similar voter laws in Kansas, Alabama and Georgia could also be invalidated. Conversely, a decision in favor of the law would embolden those states and others who might want to enact similar voting laws.
Elisabeth MacNamara, president of the League of Women Voters, said that upholding the Arizona statute would have a "chilling effect on voter registration overall, and specifically on citizen-led voter registration drives." She told reporters on a conference call that young and minority voters are much more likely to lose out if the state law stands.
"Independent voter registration drives are critical to democracy," MacNamara said.
Barbara Arnwine, who leads the Lawyers' Committee For Civil Rights Under Law, argued that the Arizona law "eliminates safe harbors" for voter registration that the NVRA guarantees.
Arizona, for its part, does not question that the Constitution gives Congress, rather than state governments, the final word on what voting laws are legitimate. Arizona instead argues that Prop 200, which was designed to prevent illegal immigrants from registering to vote, doesn't violate the terms of the NVRA.
"In sum," Arizona writes in its brief, "this Court should find that the NVRA does not preempt Proposition 200's evidence-of-citizenship requirement."