By Kate Woodsome

WASHINGTON — The U.S. Supreme Court heard arguments Monday on whether the state of Arizona has the right to craft its own voting laws to prevent illegal immigrants from casting ballots, a process critics say opens the door to discrimination against legal voters.

Arizona, which shares a border with Mexico, has some of the strongest anti-immigration laws in the United States and the voting rights case is the latest in its efforts to deal with non-U.S. citizens illegally in the state.

It is asking the Supreme Court to uphold a 2004 state law requiring local voting applicants to provide physical proof of citizenship, such as a birth certificate, passport, tribal forms or a driver’s license.

Opponents of Arizona’s voter-approved Proposition 200 say it violates the decade-old National Voter Registration Act, a federal law requiring voting applicants to state they are U.S. citizens without providing any proof. People caught lying can face perjury charges.

Arizona Attorney General Tom Horne argued the constitutionality of Proposition 200 before the Court Monday, saying an “honor system” is not strong enough to prevent voter fraud.

Jesus Gonzalez is the lead plaintiff in the case. He tried to register to vote right after becoming a U.S. citizen but was rejected twice by state officials. Gonzalez used both his driver’s license and his naturalization certificate number, but officials said they still could not confirm his citizenship.

Civil rights groups supporting Gonzalez say his story is not uncommon. In a legal brief submitted to the court, the groups say more than 31,000 voting applicants were rejected between January 2005 and September 2007. Of that number, 11,000 eventually succeeded in registering to vote after repeated attempts.

The groups say Proposition 200 violates the U.S. Constitution “because it requires naturalized citizens – predominantly Latinos and Asians – to surmount additional and unique hurdles to exercise their fundamental right to vote.”

“The unique obstacles presented by the law effectively relegated this population to second-class citizenship,” they write in the brief.

The Obama administration is on their side, although it is focusing on another aspect of the case. It has filed court documents supporting the ruling of a federal appeals court, which ruled against Proposition 200 because it said federal law overrides state law.

The outcome of the case could determine how other states approach the issue. If the Supreme Court upholds Arizona’s request to determine its own voting guidelines, other states could follow suit, opening the door for new sets of rules like Florida’s attempt in 2005 to require voter applicants to prove their mental capacity.

Voter rights groups, including the Constitutional Accountability Center, expressed cautious optimism after Monday’s court arguments.

“A majority of the Court, including Justice [Anthony] Kennedy, appeared to recognize that the entire point of having a single federal form was to streamline the voter registration process, and that approving Arizona’s law would pave the way for a patchwork of 50 state forms,” Doug Kendall, the group’s president, said in a statement.

Even after the Supreme Court decides on this case, the battle over immigration is far from over. Arizona is at the center of a national debate on how to secure the country’s borders and treat the estimated 11 million undocumented immigrants in the U.S. The issue is being tackled by lawmakers in Congress and advocacy groups across America.