The U.S. Supreme Court this week approved a solution to what is no apparent problem. Unfortunately, the fruit of this ruling may be a bigger problem -- one with an insidious, long-term effect on the workings of American democracy.

By a 6-3 vote, the court upheld a voter identification law from Indiana that is often described as the strictest in the country. It did so despite finding no evidence of the sort of voter abuse that the law was supposed to remedy. What was decisive was the finding that there also wasn't "any concrete evidence of the burden imposed on voters who now lack photo identification."

That the burden isn't set in concrete does not make it less onerous for the poor and disabled who are likely to struggle to exercise a fundamental right of American citizenship. Under the Indiana law, voters must present photo ID such as a driver's licence or passport. Those who do not drive can get a free photo ID card from the state, but that requires something like a birth certificate or a passport, too. Those without such ID can cast a provisional ballot but must appear at the county clerk's office within 10 days to justify their situation.

What might be a mild inconvenience to people of means and mobility presents a problem for others. In a perfect world, the common-sense argument would prevail: Photo ID is required for so much else in life, it should also apply for voting.

But common sense also says something stark about the motives of those pushing the law. The poor are the group that tends not to have photo ID and they tend to vote Democratic. The Indiana law was passed by Republicans without a single Democratic vote.

The dissenting opinion of Justice David H. Souter said it best. Noting that there was "no evidence of in-person voter impersonation fraud in a state, and very little of it nationwide," it said Indiana should have justified even a slight burden on people. "The interest in combating voter fraud has too often served as a cover for unnecessarily restrictive electoral rules."

Indeed it has. And the Supreme Court, which in the Bush era has a conservative Republican tilt, has once again delivered the partisan goods. Seven states including Indiana already require voters to produce photo ID before they can cast their ballots (Pennsylvania requires only first-time voters to show proof of identity; it doesn't have to be photo ID -- a current utility bill or a firearm permit will suffice).

Unfortunately, the danger is that this Supreme Court ruling -- echoing Justice Souter's words -- will serve as cover for more unnecessarily restrictive electoral rules.