Arizona is once again embroiled in a fight against the federal government at the Supreme Court of the United States. The Court heard arguments on Mar. 18 in Arizona v. Inter Tribal Council of Arizona.

In earlier years people had to go to their county seat of government–typically the county courthouse–to register to vote in a system that made it very difficult to commit voter registration fraud. A federal commission is authorized by the National Voter Registration Act of 1993 (NVRA, or “Motor Voter”), which was pushed and signed by Bill Clinton, to develop a federal form for mail-in registration.

Arizona passed a law requiring people registering to vote by mail to include proof of citizenship. It was designed as a modest attempt to prevent illegal voting by foreigners that could undermine the legitimacy of the election returns in the democratic process.

The record in this case includes over 200 people who had submitted fraudulent voter registrations, who later swore under oath to a commission investigating this matter that they were not even U.S. citizens. They say workers from groups like the now-defunct ACORN–who were getting paid for each registration form they turned in–talked them into signing it, and that these individuals did not know it was a crime for them to do so.

NVRA requires states to “accept and use” the federal form. Arizona argues it accepts and uses the form, and that adding the requirement for someone to attach proof of citizenship is allowed. The plaintiffs and the Obama administration argue that if you add anything to the federal requirements, you are not accepting and using the federal form. This case will turn in part on which side the justices take on that issue.

Usually when federal law conflicts with state law, it is resolved under the Supremacy Clause in Article VI of the Constitution, whereby federal law trumps state law under certain circumstances. Instead of the Supremacy Clause, this case will be decided under the Elections Clause in Article I of the Constitution. That provision says that states are primarily in charge of voting and elections, but “Congress may at any time by law make or alter such regulations …”

There is a large body of Supreme Court precedent interpreting the Supremacy Clause. This case may turn on whether the Elections Clause works by the same rules, or instead if there is a different framework that determines when federal election law trumps state election law.

It is unclear which way this case will go, with some justices sending signals one way or the other.

Justice Ruth Bader Ginsburg said, “Congress did specify how citizenship was to be handled. And it was to be [signing the form where you declare you are a citizen, under] penalty of perjury.” She added she understands NVRA as saying, “each state must accept and use the federal form, period. That’s the end of it.”

Justice Antonin Scalia seemed to fault Arizona for not making certain claims earlier in the litigation. But Arizona Attorney General Tom Horne explained that this lawsuit began under his predecessor Terry Goddard, who is a Democrat, and that Horne did not know why Goddard did not think to use a different strategy.

Scalia also seemed sympathetic to Arizona’s argument. For example, he remarked that the federal form requires nothing to show the individual is a citizen except, “check off, ‘I am a citizen,’ right? So it’s under oath. Big deal. If you’re willing to violate the voting laws, I suppose you’re willing to violate the perjury laws.”

Going into yesterday’s argument it was possible that two justices, Chief Justice John Roberts and Justice Anthony Kennedy, were swing votes in this case. We should find out by late June which side prevailed.  

Breitbart News legal columnist Ken Klukowski is a fellow with the American Civil Rights Union.