Justice Anthony Kennedy regards himself as a teacher. The main role of the Supreme Court, he has said, is to instruct Americans about the Constitution’s fundamental values so they know what it takes to preserve American democracy.

In Shelby County v. Holder, which the Supreme Court will hear this month, he is likely to cast the deciding vote between the conservatives and moderate liberals in a critical choice about the essence of democracy — the right to vote. The case presents a clash between America’s national commitment to racial equality and Alabama’s contention that states have “the constitutional prerogative to regulate their own elections.”

In other landmark cases, like a 2003 decision recognizing privacy rights and a 2005 case striking down the death penalty for juveniles, Justice Kennedy voted for fairness. In these instances, he was a moralist, concerned about constitutional values yet willing to balance the importance of court precedents against the weight of the most salient facts. That approach should lead him to the fair result in this case, too.

The issue in Shelby County is whether Section 5 of the Voting Rights Act, viewed as the nation’s most effective civil rights law, remains necessary to prevent racially biased voting laws in nine states and parts of seven others with egregious histories of discrimination against minority voters.