Hedgepeth ex rel. Hedgepath v. Washington Metropolitan Area Transit Authority, 386 F.3d 1148 (D.C. Cir. 2004) (available here). Writing for a unanimous court, Judge Roberts rejected Fourth Amendment and Equal Protection Clause challenges to the arrest and detention of a twelve-year old girl for eating french fries on a Metro train. The case received some media attention because of its extreme facts--as Judge Roberts noted in the first line of his opinion, "[n]o one is very happy about the events that led to this litigation."
This doesn't look like a very good decision on his part, from what I could see looking over the link. It doesn't look as though the officers ever had to stand trial before a jury to see if their actions were reasonable. The district judge had simply ruled summarily, as far as I could see. But if an action by the officers is taken without warrant, those affected by it have a right to take their case to a jury. The jury could still decide whether or not the action was reasonable under the circumstances, but a judge should not decide beforehand.