There has never been a whit of evidence that restoring voting rights has any negative impact on society, and yet disenfranchisement laws have a long and often racist pedigree in American history. States passed them in the 19th century to block African-Americans from voting. Today about six million people nationwide are disenfranchised because of a criminal record, with blacks disproportionately burdened. In Maryland, nearly two-thirds of people who can’t vote because of a felony conviction are African-American.

The governor’s veto was all the more vexing given what has been happening in Baltimore, where residents — mostly poor people of color — have erupted in outbursts of anger and frustration because they feel they have little say in the direction of their communities. Mr. Hogan could have supported the law and reaffirmed that Maryland values the voices of all its citizens. Instead his veto means that 40,000 of them will have to wait until the Legislature reconvenes next January for a veto override vote.

Mr. Hogan’s action is out of step not just with common sense, but with a growing segment of his own party. In recent years both red and blue states — from Texas to Connecticut to Alabama to New Mexico — have reduced or eliminated barriers to voting for people coming out of prison. Maryland ended its own lifetime ban on voting for those with felony convictions in 2007.

This is a moment of great promise for new efforts to reform the nation’s criminal-justice system. Disenfranchising people who are already back in their communities is nothing but punitive and counterproductive, and dismantling such laws should be an easy call.