by Jeff Jacoby

About the author: Jeff Jacoby is a nationally syndicated columnist.

Death penalty opponents frequently argue that capital punishment is racist, meted out disproportionately to blacks, especially blacks who kill whites. If there is any city where that argument ought to hold sway, it is Washington, D.C., an overwhelmingly black community that is acutely sensitive to questions of racial justice.

Indeed, until recently, Washingtonians were solidly against the death penalty. A 1992 ballot measure to establish capital punishment in the district was crushed by a ratio of 2 to 1. Among the leading opponents was Marion Barry, the once and future mayor, who forested D.C. neighborhoods with signs proclaiming, “Thou Shalt Not Kill.”

But five years later, Washington residents—particularly its black residents, who comprise more than two-thirds of the city&rsquo...