Cops cannot legally fly around with the FLIR on looking for heat sigs. They must have reasonable grounds to believe that a grow is going before they can get a warrant for FLIR overflying and investigating. Remember, cops are not supposed to even investigate people or property unless there is some reasonable grounds to believe a crime is being committed...not a hunch, but evidence.
Copters are not a big worry anymore and only now and then will they find a grow accidentally...always best to be careful but no big deal.
They may not be violating rights with FLIR but there's lots of aerial surveillance in my area. Except for this year. Too much rain messed up so many plants, we didn't see the usual amount of choppers.