One of the most interesting and significant recent Supreme Court decisions concerned the Indiana voter identification law, in which the court by a 6-3 vote upheld the law despite zero evidence of in-person voting fraud in the state. In a major surprise, Justice John Paul Stevens led the opinion, saying the state’s interest in preventing such fraud justifies the Legislature’s action. Stevens did leave the door open to challenges to other states’ laws if they create too much of a burden on many voters.

[IMGCAP(1)]Indiana’s law was better by far than the awful Georgia law that was overturned by the courts; in Indiana, the state would provide voters with the appropriate government-issue photo ID for free, while Georgia charged a significant fee, the equivalent of a poll tax. But Indiana’s requirements are plenty burdensome.

If a person cannot present a passport, driver’s license or other similar form of official identification, he or she must supply an official document, such as a birth certificate, to get the free ID, and getting a copy of a birth certificate is quite costly. The fact is that many elderly people and many poor people don’t drive, don’t fly and don’t have copies of their birth certificates.

The voter ID issue has divided sharply on partisan lines. Republicans have pushed hard for photo requirements in many states, and Democrats have resisted. Republicans have been passionate about the cancer of voter fraud, and Democrats have brushed that issue aside while being equally passionate about expanding voter access. The decision is not going to open the floodgates to dozens of onerous statutes, but it does create running room for more controversy in this area, and it leaves an opening for Congress to think through and perhaps act in a way that will bring some balance and uniformity on this issue for voters in federal elections.

Is there voter fraud? Yes, there is — but it is not the kind done in person on Election Day. The real voter fraud for which we have evidence is in voting by mail. We know, for example, what happened in one of the incredibly rare cases where an election result was actually overturned — in the 1997 Miami mayoral race, when courts threw out 5,000 absentee ballots, removed presumed winner Xavier Suarez and replaced him with his opponent, Joe Carollo. Thirty-six people were charged with absentee ballot vote fraud (most working for the Suarez campaign, but a couple on the Carollo side as well).

A part of the problem was the peculiarity of Florida law that made it easy to forge absentee ballot results, but there were and are larger problems with voting by mail. There is no zone of privacy like the one that comes with going into a voting booth and closing a curtain to all, including one’s spouse, boss or pastor. There is a great temptation to coerce or sweet-talk older or slower voters into letting campaign workers “help” them fill out their ballots. And when the ballots are filled out and mailed in, sometimes several weeks before the election itself, they can sit unguarded in a municipal building or voting official’s office, with the potential for partisans inside or outside the office to jettison some or skew others.

As for in-person polling place voter fraud, it was widespread at the turn of the 20th century (which led to such path-breaking reforms as the Australian ballot and the norm of the secret ballot), and it certainly took place in sizable amounts a few decades ago. But there is no credible evidence that it is a serious problem now.

I do not have any Pollyannish notion that most people in politics are good and fair — lots of ’em on both sides would steal an election in a New York minute if they could. But frankly, engaging in systematic in-person voting fraud is way too much effort for way too little payoff. To be sure, there are occasional instances of either sloppiness or chicanery in voter registration drives, and individual instances of wrongdoing. But every allegation of big-time fraud ends up being shot down by the evidence.

Elections need to be fair, and fraud is a real concern, especially in an era where the stakes are very high and the parties are close enough that many elections will be decided by razor-thin margins. But I would have more confidence in the concerns that legislators in states like Indiana and Georgia raise if they were equally passionate about fraud in voting by mail. But for the most part — with exceptions such as The Wall Street Journal’s John Fund — the same people who scream from the rafters about rampant in-person fraud say nothing at all about the other kind (could it be that more of “their” voters vote absentee?).

In many states, the safeguard against forged absentee ballots is a signature match. It is done with considerable sophistication these days. If a simple signature match — one in which the initial signature does not have to be accompanied by any official government-sponsored photo ID — suffices for votes-by-mail, why is it not enough for votes at the polling place?

This is not just an issue of motive and fairness. The fact is that no-excuses absentee voting and voting by mail are expanding rapidly out there, and may be as much as 30 percent or more of all the votes cast in November. If the trends continue, they may soon be the norm. At that point, fraud will be a huge concern.

In the meantime, we will have to deal with the larger questions posed by voter ID laws. I do not think, in principle, that requiring a photo ID is evil or onerous. An official photo ID can protect voters against charges that they are ineligible to vote. I agree with civil rights activist Andrew Young that a photo ID would be a huge help to poor people who are often victimized by huge fees they are charged to cash paychecks because they lack any such identification.

But there are certain clear principles that need to be applied. Any such ID has to be offered for free — including no-cost access to whatever support documents are required. In a free society, no one should have to pay to vote, and there should not be any unequal burden on those citizens who want to vote. Not only should the ID be free, but it must be readily accessible — in multiple places convenient to the poor and elderly, and through mobile vans to reach those who can’t get out easily to the fixed sites.

With these conditions, a voter ID is not an undue burden. But to get to that point requires two things: federal guidelines for the states, under Congress’ constitutional power to regulate federal elections, and federal money to make the system work for all. This issue is significant and controversial enough that it ought to be on Congress’ agenda this year. But Congress’ track record on election reform this year suggests that the chance of that happening is zero.

Norman Ornstein is a resident scholar at the American Enterprise Institute.