Comment by jen_h

This reminded me of a case back in 2003...the 9th Circuit Court of Appeals ruled against the FBI in a case where they were tripping "recovery mode" to surreptitiously monitor drivers under Federal investigation:

http://news.cnet.com/Court-to-FBI-No-spying-on-in-car-comput...

The court ruled against the FBI here, apparently not for anything related to privacy, but rather due to the fact that such surveillance could constitute an interruption in emergency services.

Note also that the decision is only binding in states that fall within the 9th Circuit's jurisdiction. (And no clue whether this decision applies also to local law enforcement; would assume that it does, but IANAL/LLE).