 On 31 March 2011, Vorotnikov was arrested again in an unrelated incident, for assaulting a police officer at an unsanctioned political rally.Activists aligned with the group Strategy-31 were demonstrating in favor of proper enforcement of Article 31 of the Russian constitution, which guarantees the right to peaceful assembly.The demonstration turned into an ugly confrontation, after activists doused police officers with bottles containing their own urine.