[logfromblammo]

And the de jure standard answer is "because you had a reasonable suspicion I was committing a crime," or "I don't answer questions without legal counsel present."

Of course, since many cops will retaliate against smartasses, the de facto standard answer is "I don't know. Why did you pull me over?" This is always truthful, correct, and non-incriminating, because you can't be expected to read the cop's mind.

[kelnos]

Yep, totally. I usually use the wording "I'm not sure", or, better, "I can't be sure", since "I don't know" is often not entirely truthful.