Liberals have good reason to be nervous whenever the Roberts Court decides to hear a voting rights case. It has upheld voter ID laws on the one hand, and struck down a crucial provision of the Voting Rights Act on the other. Today, however, was a rare exception. A unanimous Supreme Court refused to strike down Texas’s “one-person, one-vote” reapportionment, foiling an attempt to tilt power toward more conservative areas of the state.

This is good news, but it’s also a qualified victory. The Court’s opinion in Evenwel v. Abbott leaves open the possibility that states could undermine “one person, one vote,” and at least some red state legislatures are likely to try it.

Today’s case concerned the application of the Warren Court’s landmark decisions in Baker v. Carr and Reynolds v. Sims, which require a “one person, one vote” apportionment standard for legislative districts (with the obvious exception of the U.S. Senate, where each state, no matter their size, is granted two senators). Generally, this apportionment is done by measuring total population. A suit brought against the state of Texas, however, argued that the Equal Protection Clause of the Fourteenth Amendment required voters, rather than residents, to be used as the denominator. If this argument had been accepted, it would have had the effect of substantially diluting minority representation—exactly the outcome Baker and Sims were trying to prevent. (Racial minorities and the poor are less likely to vote than whiter and wealthier constituents.)

In a unanimous opinion written by Justice Ruth Bader Ginsburg, the Court rejected this argument. “[T]he rule appellants urge has no mooring in the Equal Protection Clause,” concluded Ginsburg. “Adopting voter-eligible apportionment as constitutional command would upset a well-functioning approach to districting that all 50 States and countless local jurisdictions have followed for decades, even centuries.” For now, these practices will remain in place, and the Supreme Court will not stand the Equal Protection Clause on its head by requiring states to dilute minority representation.

So far, so good. But this doesn’t settle the issue politically. The Supreme Court said that states are not required to apportion legislative district by voters, but it didn’t forbid the practice either. It is very likely that some conservative legislatures will do exactly this in 2020, when the next Census rolls around.