Elmer Stoltzfoos Fisher, 22, of Paradise, was found slumped over and asleep in a buggy that was moving very slowly in the first block of North Ronks Road on Sunday night.
East Lampeter Township police received a call at 9:05 p.m. Sunday from off-duty Quarryville police officer Jesse Blank about the possible DUI.
A car driven by Blank came up behind the buggy, which he said was moving at a walking pace. The horse was pulling the buggy along the road, straddling the center line.
Sensing a problem, Blank stopped his car. His passenger, Nate Perry, got out and approached the buggy on foot. Stopping the horse, Perry found Fisher slumped over and asleep.
Perry pounded on the buggy door until Fisher was awakened.
Police said Fisher displayed signs of intoxication, with the strong smell of alcohol on his breath and bloodshot, watery eyes.
A breath test showed his alcohol level at 0.18 percent.
Fisher was arrested for drunk driving, police said.