Anarchy: Rush Hour

You will unlock this trophy simply by playing Story mode events. The police start chasing you when you hit traffic and get them on alert. It will be a natural progression for you, as all the races in the city are littered with police cars cruising around and it's virtually impossible for you to have a perfectly clean race. Almost to the point where it will become natural for you to have the police around in every city race event. There are few Circuit events where there is no traffic or police, but you should have nothing to worry about and no trouble getting this on your first try.