The state of Indiana has the most restrictive voter I.D. law in the country. Show up at the polls without a currently valid, government-issued photo I.D., and you can’t vote. I realize that to many Americans, that doesn’t sound like much of a burden. And for many Americans, it isn’t.

But it is a very substantial burden for many groups of eligible voters, including the elderly who don’t drive, college students, and the poor who don’t own cars. There’s a great deal of overlap between those who are unduly burdened by this law and Democratic voting constituencies. It’s probably no coincidence, then, that support for Indiana’s restrictive law came from Republicans in the state legislature.

Indeed, the law is a “solution” looking for a problem, since Indiana has been unable to identify a single case of in-person voter fraud occurring in its history. In fact, studies have shown that widespread, in-person voter fraud simply does not exist, whereas many eligible voters do in fact lack the I.D. that laws such as this require.

No matter. Today, by a 6-3 vote, the Supreme Court rejected a challenge to the Indiana law. The Court that should be the staunchest defender of American democracy has enabled a state, without substantial justification, to erect barriers to voting. As we approach a presidential election with the possibility of a record voter turnout, the last thing our democracy needs is more roadblocks to voting.

There’s a small ray of hope, however, as the Court left the door open to future challenges to the Indiana law and to voter I.D. laws in other states. In the meantime, today’s ruling once again underscores how important the Supreme Court is to the rights of every American, including that most fundamental of rights — the right to vote.