Need for Speed

The hardest part about completing the Outlaw campaign and challenges is finding the police. You can drive around town for lengthy periods at time without running into the cops. There is one area at the South Port that always has a cop that you can find.

In the slim chance there is no cop when you arrive, just leave the area for a few mins and come back. It's possible the cop was chasing someone else, but it will respawn shortly. Here is a video that shows you exactly where it's at.

This achievement pops after the mission 'Assume the Position', a trial where you just run with the Outlaws. Once the race is over, you'll get a call to go to the diner where all is revealed.