>But my assessment would be that even though it's trespass, it's not actionable (no damages), and it's not a Fourth Amendment violation because it's not actually part of the search, but merely incidental to it
But it's done when the officer isn't allowed to (otherwise) search -- before he's had any contact with the driver or even looked inside the car.
You have to think of the causal chain that leads to recovery of evidence. Marking your tire with chalk is part of the causal chain--if the police didn't do it, they wouldn't know you had broken the law. Touching your car during a stop is not part of any causal chain--it's a separate tort that happens to be non-actionable because there is no damages.
Say a police officer stops you for running a red light. At that point, he has no suspicion that would justify a search. I tries to tap on your door to get you to roll down your window, and his ring scratches your car. That is a trespass to chattels, and it's actionable because it has resulted in damage to your car. After you roll down the window, he sees someone snorting cocaine in the back seat. He then searches your car, and recovers tens of kgs of drugs.
Was there an illegal search? No. Even though scratching your car was a trespass, and even though you can still sue for the cost of fixing the scratch, that trespass had nothing to do with recovering the evidence of drug crimes.
I appreciate the analysis of the cocaine detection, and the torts, but the question was about the evidential legality of touching your rear tail light. That was not necessary to conduct the stop and (by supposition) there is insufficient evidence for a search (beyond what he can ordinarily see), etc.
Are you saying that e.g. the cop's fingerprint on the tail light could not be used as evidence, because it was an illegal trespass?
Ah, okay, I get it now. In that case, I think the cop’s fingerprint could be used as evidence if the cop went missing. Say the cop opened your bag and dug through it without a warrant. That’s clearly a 4th amendment violation. That would result in exclusion of evidence obtained from the search of the bag. But if the cop went missing, fingerprints from the bag would be admissible as evidence of the fact that he had searched the bag and interacted with you. Whether the later search is legal would depend on the specifics of that search.
I'm trying to follow this discussion (because it is interesting) and I am a little lost about this fingerprint thing. What does leaving a fingerprint on a taillight accomplish for the officer?
>Before cameras were installed on the dashboards of most police cars, tapping the taillight was an inconspicuous way for officers to leave behind evidence of the encounter, according to The Law Dictionary. If something were to happen to the officer during the traffic stop, their interaction with the driver could be traced back to the fingerprints left on the vehicle. This would help other police officers track down a missing member of the force even without video proof of a crime.
Hence the link in the comment I referred to: http://mentalfloss.com/article/502605/reason-police-officers...
>But my assessment would be that even though it's trespass, it's not actionable (no damages), and it's not a Fourth Amendment violation because it's not actually part of the search, but merely incidental to it
But it's done when the officer isn't allowed to (otherwise) search -- before he's had any contact with the driver or even looked inside the car.