Lyle Denniston, the National Constitution Center's adviser on constitutional literacy, examines two constitutional provisions at the heart of a new controversy over who controls the right to vote.

The statement at issue:

"The constitutional rights, powers, and privileges of establishing voter qualifications, including voter registration requirements, are incidents of state sovereignty protected by Article I, Section 2 of the Constitution, the Tenth Amendment, and the Seventeenth Amendment. This power includes the power to obtain information the states deem necessary to assess eligibility or voter registration applicants, and to enforce voter qualifications. A mere oath without concrete evidence of citizenship…does not suffice."

– Excerpt from a lawsuit, now making its way through federal courts, by the states of Arizona and Kansas, seeking to force a federal agency to include a proof-of-citizenship requirement on federal forms for registering voters under a 1993 federal law. The lawsuit came up for a hearing last Monday in a federal appeals court in Denver, so is now awaiting a decision.

We checked the Constitution, and ...

One of the gestures toward states' rights that the Founders made in writing the Constitution was to give the states a primary role in deciding who gets to vote – not only in state and local elections, but also in federal elections. But, to protect national interests of the new government they were setting up, the Founders also gave Congress a veto power in this area. It has never been quite clear how the two provisions were supposed to work together, instead of in conflict, and that is at the heart of a new controversy over who controls the right to vote.

The controversy arises at the intersection of two recent trends in the management of elections. First, a number of states, out of a fear of voter fraud (especially, a suspicion that non-citizens who are illegally in this country are voting), have been imposing tight new ID requirements to ensure that only citizens get to vote. Second, Congress and a federal election management agency have been proceeding, under a 1993 law, to try to ensure that barriers to registration are eased so that more people get to go to the polls.

Those contrasting trends have been made more difficult to sort out, as a constitutional matter, because the Supreme Court in a major ruling last year gave guidance that points in two directions: buttressing federal power to try to make registration requirements uniform, but virtually inviting states to sue to try to get their way in enforcing their own registration rules.

The Court's decision in mid-June 2013 in Arizona v. Inter Tribal Council of Arizona was supposed to clarify the competing national and state roles, under the National Voter Registration Act of 1993 and also under the Constitution. That case arose because the voters of Arizona in 2004 had passed so-called "Proposition 200" saying that, because "illegal immigrants have been given a safe haven in this state" and were attempting to vote, it was necessary to impose a requirement to show an official ID in order to be registered to vote.

Arizona, later joined by Kansas, began asking the agency set up by Congress to carry out the National Voter Registration Act (the Election Assistance Commission) to add that ID requirement to the federal voter registration form that Congress had mandated, at least for federal elections. The federal form is a key document, because no state wants to conduct federal and state elections separately, under different registration systems.

The federal Commission resisted the requests, concluding that the form was sufficient as is – that is, requiring an applicant seeking to register to simply swear, on the form, that they are a citizen. (In passing the 1993 Act, Congress had considered, but rejected, a proposal to add a voter ID requirement to the conditions for registering to vote in federal elections.)

Challengers to the Arizona demand sued, contending that states were obliged to use the federal form – at least for federal elections – without adding a requirement of documentary proof of citizenship, a requirement that the challengers argued has the effect of discouraging voting. It was that challenge that the Supreme Court had agreed to settle in the Inter Tribal Council case.

Addressing the two provisions in the Constitution, the Court first appeared to lay down a very broad rule on when state election law requirements had to yield to those enacted by Congress. The Court's main opinion seemed to say that states do not get the benefit of the doubt when they pass election laws that appear to be, or are, different from what Congress had enacted.

But that decision went beyond that initial point, adding that states do have the primary role in deciding who gets to vote, and that states wishing to enforce a voter ID requirement for registration were free to ask the federal Commission to tack that onto the federal form. And, it added, if the federal agency resists, the states have a constitutional right to sue to obtain the clear authority to enforce their own voter registration requirement – that is, in this instance, the proof of citizenship mandate.

Arizona and Kansas then went back to the federal Commission with that very request, and that agency continued to resist. States, it said, cannot compel that agency to change its form in a way that the agency itself does not think is necessary to carry out state registration rules. The federal form, it noted, has an oath requirement, and that is enough.

The two states then sued, as the Supreme Court had clearly seemed to suggest that they do, and the case has been unfolding in federal courts over the past year. So far, the states are winning. A federal judge in Wichita ruled in March that it was not necessary to clear up the competing constitutional arguments about who – the national government or the states – has the power to control who may register to vote. Instead, the judge ruled that the 1993 law, by its own terms, requires the federal Commission to grant state requests to add to its form the specific requirements that a state says are necessary in order to implement those requirements.

The Commission and a number of advocacy groups supporting it have now taken the case on to the Tenth U.S. Circuit Court of Appeals. If that court agrees with the federal trial judge that the issue is settled by the terms of the 1993 law, the constitutional dispute will drop out of the case – at least until the issue moved on to the Supreme Court.

But if the appeals court concludes that the federal law does not settle the issue, it then may have to try its hand at sorting out how the two provisions of the Constitution are supposed to work. That would be a challenging task, on its own, but a task made even more difficult by the uncertain signals the Supreme Court sent when it made its effort to sort out the controversy. There is thus much more to come in this potential reopening of questions about what the Founders intended.

Philadelphia's National Constitution Center is the first and only nonprofit, nonpartisan institution devoted to the most powerful vision of freedom ever expressed: the U.S. Constitution. Constitution Daily, the Center's blog, offers smart commentary and conversation about constitutional issues in the news, drawing insights from America's history and a variety of expert contributors.