BikePortland Blog reports that a Multnomah County judge has ruled that the ability to skid with a brakeless fixed gear bicycle does not meet the Oregon statutory requirement for a bicycle, which "must be equipped with a brake that enables the operator to make the braked wheels skid on dry, level, clean pavement strong enough to skid tire."
Many fixed-gear bicycle enthusiasts ride without brakes, using technique and strength to stop their bikes. Because fixies do not freewheel, locking the legs stops the motion of the wheels. Hopping up or "skipping" the rear wheel a moment before locking the legs makes this a lot easier.
Many armchair cycling lawyers have argued that skid stops on a fixie meet the law's requirement that a brake must be able to induce a skid.
From the comments, it appears Portland Police are now cracking down and ticketing brakeless fixie riders instead of cracking down on the real traffic problems in Portland. Automobiles killed somewhere around a dozen cyclists last year in Portland; how many deaths were caused by brakeless fixed-gear riders?