A federal appeals court reversed a dramatic ruling last year that California’s death penalty system is unconstitutional, using decidedly undramatic grounds to do it.

Lawyers for Ernest Dewayne Jones, who was sentenced to death 20 years ago, argued his execution should be barred in part because the length of his wait showed the arbitrary nature of the state’s system. A federal judge agreed in a 29-page decision that helped triggger a national debate on the efficacy of capital punishment.

U.S. District Judge Cormac Carney in Santa Ana wrote that “for the random few for whom execution does become a reality, they will have languished for so long on death row that their execution will serve no retributive or deterrent purpose and will be arbitrary.”

On Thursday, however, the U.S. Court of Appeals in San Francisco weighed in, citing not the Eighth Amendment’s bar on cruel and unusual punishment — which may proscribe arbitrariness — but instead the dry rules governing the habeas corpus petition Jones filed.

Jones’s argument is a ‘‘novel” legal proposition, the three- judge panel wrote, and thus has no place in a petition that seeks to apply federal law only as it currently exists.