You've got it backwards. Whren means that what matters is the objective circumstances, not what the officer is thinking. If Whren hadn't taken an illegal turn, the officer couldn't have offered some subjective reason for pulling him over.
The problem here is that the law also applies to the officer's behavior, and intent matters.
The officer requires probable cause for pulling the person over. The illegal turn is not the probable cause that the officer is using. The illegal surveillance is, but the officer is lying about that.
That's an explanation of the legal theory, correct?
The other side of the issue is the practical outcome. If typical defendants don't have the resources to examine whether the objective reasons given for stops are legitimate, then the distinction doesn't seem very comforting.
No, that's an explanation of the practical outcome. It's much harder to force the typical defendant to argue about what the officer subjectively believed than to point to the objective facts.
I read higherpurpose's concern as being about the use of secret surveillance information for targeting vehicles for searches. My understanding was that they saw that as, at least, a subversion of the way a just system ought to work.
It looks like higherpurpose is over-reading "pretext" to be a false statement, but I think I agree with the sentiment that I don't really want police focusing their attention based on information that they later obscure (I would not be surprised if there are exceptions to this that I would agree with).
So the question I was formulating was about the incentive this creates for the officers (to pull people of interest over for whatever the hell) and the differing ability of those people to challenge the stop. I guess on further thought that isn't a particularly interesting question (driving is easy enough to nitpick and find a legitimate pretext that will withstand scrutiny).
Anyway, when I said 'legal theory', I meant that you were explaining the particulars of that decision more than you were addressing the concerns about targeting, and when I said 'practical outcome', I was thinking about how it would influence behavior of law enforcement more than how it would play out in court.
