There's a reason why Republican-controlled legislatures are enacting voter ID laws: The voters most likely to be without the required identification are the poor and the elderly, prime Democratic Party constituents whose turnout rate is lower than average to begin with.

This week the U.S. Supreme Court's conservative majority ruled 6-3 to endorse states' right to erect a hurdle to full participation of the qualified electorate in choosing our leaders.

The court opinion authored by Justice John Paul Stevens admitted there was no evidence in the case record of voter fraud in Indiana but also said that plaintiffs had failed to prove that the law imposed an undue burden on voters. The court found that a state has legal justification to mandate such requirements.

A lengthy dissent by Justice David Souter, joined by Ruth Bader Ginsburg, argued that the contested Indiana law imposes nontrivial hardships on tens of thousands of voters and would lead a significant percentage of them to not cast ballots.

In Texas, evidence of voter fraud that would be prevented by a photo ID requirement also has been lacking. A task force mounted by Texas Attorney General Greg Abbott in recent years has spent millions of dollars to make a handful of indictments, all of people who registered illegal voters. The measures that narrowly failed in the Legislature's last session would not have detected those violations.

Academic studies indicate a substantial suppression of turnout in states with voter ID laws, disproportionately among the elderly, the poor and minorities. No state has produced a significant number of cases in which people illegally cast ballots on Election Day by impersonating someone on the voter rolls. That is the rarest form of vote fraud, far more difficult to pull off than manipulation of mail-in ballots or possible in-house tampering with electronic voting machines.

Now that the Supreme Court has opened the door, expect another protracted fight in the next session of the Texas Legislature over a divisive voter ID statute. Voters going to the polls in November should find out the legislative candidates' position on that proposed law and choose accordingly.

If GOP legislators were sincerely concerned about the validity of election results, they would support bills to mandate a paper trail for electronic voting systems, which would make possible verifiable recounts in disputed elections. The fact that some legislators are instead promoting a bogus cure for a nonexistent problem is evidence as to their real motive.