How far can states go if they want to put in place tougher requirements for voter registration?

We're not done bickering about this yet. (Washington Post)

That was one of the key questions at stake in a big Supreme Court decision released Monday, Arizona v. Inter Tribal Council of Arizona. By a 7-2 vote, the justices ruled that Arizona could not require additional proof of citizenship on federal forms designed to make voter registration easier.

On the surface, that looks like bad news for states that want stricter standards. But the decision actually doesn't settle this debate once and for all, explains Rick Hasen, an election-law expert at the University of California at Irvine.

"The opinion opens up a huge number of questions about federal power over elections," says Hasen. Indeed, the opinion, written by Antonin Scalia, could actually give states more leeway to put in place tougher voter-registration restrictions in the years ahead.

Let's step back to see why: The Arizona case itself was fairly narrow. Arizona has had a law in place since 2004 requiring anyone who wants to register to vote to provide documentation that they're a citizen. By contrast, the federal government has set up a very simple registration form — under the 1993 "motor voter" law — that only requires an oath of citizenship. The question here was whether the Arizona initiative trumped the federal law. The Supreme Court said, no, the federal law prevails.

But, explains Hasen, Scalia's opinion essentially offered Arizona a "road map" for winning its case in the future. All Arizona officials need to do is go to the U.S. Election Assistance Commission and ask them to revise that federal form to include a proof-of-citizenship section. At the moment, however, there's no one sitting on that commission, because Congress refuses to fill it. So, Scalia noted, future courts could conceivably force the commission to include that proof-of-citizenship bit.

What's more, Hasen says, Scalia argued in his opinion that the Constitution gives Congress the power to regulate the "times, places, and manner" of federal elections, but the states still have the power to determine qualifications for who votes. That distinction could allow states to challenge certain federal rules on voting going forward, especially with regards to registration.*

"There's new ammunition here for states in making arguments against certain federal requirements," says Hasen. "The language is full of 'might's and 'may's, so it's unclear how this will be resolved in the future." He notes that the Court's four liberal justices joined Scalia on his decision, and obviously their votes could change in other cases.

For the past decade, the United States has seen a protracted state-by-state fight over who is eligible to vote and what kind of proof may be required. Very generally speaking, Republicans have often favored stricter requirements, which they claim are necessary to combat voter fraud, while Democrats have said these rules make it harder for minorities and poor people to vote. (Studies have found that in-person voting fraud is extremely rare.) The Arizona case isn't likely to put an end to those battles.

* Correction: In his opinion (page 15, footnote 8) Scalia discusses a 1970 Supreme Court decision holding that the federal government could compel states to allow 18-year-olds to vote, and says that decision has "minimal precedential value." The way I originally wrote that was totally garbled and made it seem like Scalia had cast doubt on the ability of 18-year-olds to vote. Apologies.

Further reading:

--Here's more background from the Post on the substantive debate over voter ID laws. And here's a piece from last fall finding that in-person voting fraud is very rare.

--My colleague Robert Barnes has an excellent breakdown of the Arizona case.