I got a good chuckle today while riding down the Mall. There was a motorcycle cop at the intersection of 14th and Jefferson (near the Washington Monument). A fellow bike commuter pulled up ahead of the line where one is supposed to stop and got berated by the cop because she had gone past the line! She dutifully backed up and smiled at the officer.
This type of thing only happens with US Park Police and the Capitol Hill Police. The DC Metropolitan Police aren't so strict--they have other things to worry about!