­­The Republican Party fares much better in state and midterm national elections than in presidential election years. There's an obvious reason: Fewer people vote in state and off-year elections, and these electorates tend to be whiter and more affluent. So it's really no surprise that at the state level, Republicans have been passing laws that attempt to suppress the vote in all elections, so that every electorate looks like the whiter, richer off-year electorate.

On Wednesday, however, a major Fifth Circuit decision dealt a serious blow to these efforts. Much of Texas' particularly draconian voter-ID law was struck down, and the decision will almost certainly remain in effect in November. Even more important, the court identified the core problem with these laws: Their vote suppression is racially discriminatory.

Texas' SB 14 was arguably the most stringent voter-ID law in the country. The problems with this type of law are manifest. On the one hand, voter impersonation fraud is essentially non-existent in practice and has virtually no chance of affecting an election even in theory. And on the other, these requirements fall disproportionately on racial minorities and the poor. So these laws have racially disparate effects while providing negligible legitimate benefits.

Texas' law, and the similar ones being enacted by other state legislatures, are not just bad public policy — they also run afoul of federal law. While the Roberts court struck down a crucial provision of the Voting Rights Act in 2013, Section 2 of the Act — which forbids racially discriminatory state voting practices — remains in effect. The Fifth Circuit is a conservative, Republican-controlled court, and yet a 9-6 majority found that SB 14 violated the Voting Rights Act.

The court did not decide the question of whether the law was passed with a discriminatory purpose, sending that question back to the lower courts. But it did find that the law had a discriminatory effect, which was enough to violate federal voting rights law.

The majority opinion, written by Judge Catharina Haynes, was straightforward and powerful. More than 500,000 eligible voters in Texas lack the required ID. Various forms of statistical analysis confirm that racial minorities were far more likely to be affected by these requirements, and various individual cases confirm these effects. As a result, a majority of the court upheld the District Court's determination that "SB 14 has a discriminatory effect on minorities' voting rights in violation of Section 2 of the Voting Rights Act."

The lengthy, angry dissent by arch-conservative Judge Edith Jones defended the law using reasoning that would make it virtually impossible to find any vote suppression law illegal (which of course is the point.) Jones says that because the law did not affect the 90 percent of Texas minorities that had the required ID, the fact that those without the requisite IDs were overwhelmingly people of color does not represent racial discrimination. This is a transparently illogical claim.

The four Democratic nominees on the Supreme Court are nearly certain to agree with the Fifth Circuit's decision, meaning it will almost certainly stand. As a result, SB 14 will not be permitted to go into effect in its current form.

This is a major victory for voting rights.

And it's not the only recent one, either. A federal district court held earlier this week that Wisconsin's voter ID law could be applied only if people who lack the required ID can vote by submitting an affidavit. It wasn't quite the victory that the Fifth Circuit's opinion was, but it will still make it easier for the nearly 10 percent of Wisconsin's population, disproportionately poor people of color, for which it had been made difficult or impossible to cast ballots in November.

These victories are important, but they are only battles in a long war. For voting rights as for so many issues, control of the Supreme Court will be crucial. If Hillary Clinton is able to fill the vacant seat left by the death of Antonin Scalia, the Court will aggressively enforce the Voting Rights Act, and may well also rule vote suppression laws like those in Texas and Wisconsin unconstitutional. If Donald Trump is able to appoint the median justice of the Court, the Court will (like Edith Jones) wink at the discriminatory legislation Republican legislatures pass to maintain power even as they move further and further from most of the electorate.

On this issue, like so many others, the contrast between the parties couldn't be more stark.