First, the police can often get a warrant very quickly (like, an hour) in am emergency. Second, there are some exceptions in the case of an immediate threat of

First, the police can often get a warrant very quickly (like, an hour) in am emergency. Second, there are some exceptions in the case of an immediate threat of harm or destruction of evidence. But if you have time to get and fly the drone, you probably have time to, in parallel to planning the observation -and your likely response- to get a warrant as well.