Policing in Vancouver was transformed by the labour unrest of the interwar period, culminating in a campaign carried out by a new civic regime that assumed power in response to a general strike threat. Complicating the process was that police workers were considered unreliable for policing labour disputes, especially since they unionized under the threat of a general strike in 1918. The challenge of “constituting authority” was therefore to render the police a reliable instrument against working class unrest. This study traces the development of policing through the postwar spate of waterfront strikes to the 1930s anticommunist campaign that carried the struggle into the political arena. Even as police power was being consolidated in the municipal police institution, rank and file police were undermined by tactics long used against other workers, namely labour spies and police specials. Like other workers, police resisted, modifying the process of change as a result.