In a remarkable shift, the police, previously the enforcers of Mr. Ben Ali’s rule, organized a protest of their own on the city’s central artery, Bourguiba Boulevard. They wore red armbands in solidarity with the revolution, complained that Mr. Ben Ali and his family had put cronies in charge of the security forces and demanded a trade union that could negotiate for higher wages. Tunisians were stunned to see police officers, once silent and terrifying, complaining about their working conditions in interviews with Al Jazeera.