South Dakota Gov. Mike Rounds should have exercised better judgment in considering whether to sign a bill exempting horses and bikes from drunken-driving laws in that state.

Rounds apparently aligned himself with the theory expressed by a state senator who observed that he would much rather have a drunk on a bike coming at him than a drunk behind the wheel of a motor vehicle.

So would other people.

But that theory ignores the fact that an intoxicated horse rider or bicyclist can be the cause of serious or deadly vehicle accidents in which they escape unscathed.

The South Dakota legislature offered the horse and bike DUI exemptions as part of an effort to update the criminal code.

The measure in question updates that code in the wrong way.