During oral arguments in April, the Supreme Court appeared determined to scrap the historic Voting Rights Act of 1965. The law had been challenged by a tiny utility district in Austin, Texas, that sought release from federal oversight. In questions from the bench, several high-court justices suggested that the act had outlived its usefulness and become unfair to states where it applied.

So it came as a surprise last week when the court, in an 8-to-1 ruling, preserved the act rather than strike it down as unconstitutional. Writing for the majority, Chief Justice John Roberts said the utility district could, on its own, try to opt out of federal oversight, as could other jurisdictions bound by the act. (A lower court had found that only certain government entities could seek a bailout.) Otherwise, however, the law’s key provision would remain intact.

By regulating election rules in certain (chiefly Southern) states, the civil-rights era act swept away obstacles to minority voting, improving participation and ensuring greater fairness. In 2006, Congress voted overwhelmingly to extend it another 25 years.

While praising the act’s historical accomplishments, the chief justice nevertheless noted that conditions since its enactment had changed. Further, in extending the act, Congress relied on decades-old information, perhaps treating some jurisdictions unfairly. Yet even if, as a result, the act now raised constitutional questions, the court need not rush to decide them, the chief justice wisely said. Letting more jurisdictions make their case for exemption from the law is a sensible and far less disruptive alternative.

This ruling was an important victory for the kind of judicial modesty Chief Justice Roberts implied during his confirmation hearings he would strive for. Too often in the four years since, the court has divided along ideological lines, sometimes bitterly. When that happens, fairly or not, it appears to be placing politics above the law, marring the credibility that is its only real source of power.

The court’s only black member, Justice Clarence Thomas, partially dissented from the ruling. He argued that sufficient progress has made the Voting Rights Act unnecessary. A longstanding critic of affirmative action, Justice Thomas may be the court’s most fervent backer of a colorblind reading of the law. However, as Congress saw, it is not quite time to scrap the basic protections of the Voting Rights Act. The Supreme Court was right to avoid a wholesale confrontation with the legislative branch, and to widen the door for gradual change.