Editor's note: Daniel P. Tokaji is a professor of law at Ohio State University's Moritz College of Law and the associate director of the Election Law @ Moritz project.
Columbus, Ohio (CNN) -- Arizona Gov. Jan Brewer this week vetoed a bill that would have required presidential candidates to produce specified documents to prove their qualifications for that office. Similar bills are being considered by a number of other states. Vetoing Arizona's bill was the right call, one that staved off a likely judicial challenge.
Arizona's Legislature was correct to believe it has the power to set a process for determining a presidential candidate's qualifications. The problem is that the bill it passed could keep eligible candidates off the ballot.
The push to require proof of eligibility arises from the discredited "birther" movement, which questions whether President Barack Obama was really born in the United States. Still, the birthers are right about one thing: States may ensure that a candidate for president meets the qualifications set forth in the U.S. Constitution, including that he or she be a "natural born citizen of the United States."
The authority to set procedures for assessing presidential qualifications comes from Article II of the Constitution, which gives state legislatures the power to determine how presidential electors are selected. That includes the determination whether presidential candidates meet the constitutional qualifications for the office.
Arizona's bill required an affidavit with a "long form birth certificate," which includes not only the date and place of birth, but also the names of the hospital and attending physician as well as the signatures of witnesses in attendance. Some certificates, including Obama's Hawaii birth certificate, don't include this information.
Under Arizona's bill, it appears that such a certificate couldn't even be considered in determining whether someone was born in the U.S. The bill did allow other specified records to be considered, namely baptismal or circumcision certificates, hospital birth records, postpartum medical records and early census records. But these documents may not be available to some presidential candidates, though they can produce other information -- such as a newspaper birth announcement -- showing they're natural born citizens.
States have the power to determine whether presidential candidates are qualified to serve. They don't have the power to impose new requirements that would keep qualified candidates off the ballot. Imposing additional qualifications would violate Article II of the Constitution.
The most relevant Supreme Court precedents are Powell v. McCormack and U.S. Term Limits v. Thornton, which preclude either the federal or state governments from adding to the constitutional qualifications for serving in Congress. The same principle applies to qualifications for serving as president. Had Arizona's bill been enacted into law, it likely would have been deemed unconstitutional as applied to qualified candidates who don't have the specified documents.
So what may states do if they wish to ensure that presidential candidates meet the Constitution's qualifications?
First, they should allow the birth certificates issued in the 50 states, rather than requiring information that doesn't actually appear on some certificates. Second, they should allow candidates without a birth certificate to introduce any other evidence showing they're qualified, rather than limiting them to specific documents that may not be available to some. Third, states should provide a fair judicial process for adjudicating disputes over a candidate's qualifications, which would allow for ultimate review in the Supreme Court.
This will prevent a renegade state official or state court from keeping a qualified candidate off the ballot for partisan reasons. It will also help avoid a violation of the Constitution.
The opinions expressed in this commentary are solely those of Daniel P. Tokaji.