You have a "reasonable expectation of privacy" in your back yard. Not in the street.
For the "plotting" thing they'd need a warrant.
> What these cases, among others, underscore is that the aerial surveillance doctrine only provides courts with a blueprint–not a clear, unambiguous pathway–to reach a judgment in Fourth Amendment cases.
> [16 states] have passed laws requiring that law enforcement obtain a search warrant before using drones for surveillance purposes.
[1] https://en.wikipedia.org/wiki/Aerial_surveillance_doctrine
It's not cut-and-dry, depends on the courts whim and your state.