Based on the discussion in Kyllo v the United States ( http://en.m.wikipedia.org/wiki/Kyllo_v._United_States ), (1) the justices appear to ask "is this sportsmanlike behavior?" when deciding whether a warrant is needed, and (2) the official line is "does the general public believe the police have the power in question?"
It seems to me that this currently would be struck down under Kyllo, but that if the police make a big deal about their new tool, they could eventually use it without a warrant.
It seems to me that this currently would be struck down under Kyllo, but that if the police make a big deal about their new tool, they could eventually use it without a warrant.