You're always legal to record a cop's official duty in Michigan -- disclosure of the fact that you are recording is entirely up to you -- I wouldn't unless I'm using Qik (iPhone app) live upload -- "juicy" recordings tend to get snatched otherwise.
Consider getting a dedicated recorder that is always on. Sometimes things go down hill faster than you can start recording.
Aside from cops, you may record any convo you are a party of or anywhere a person doesn't have a reasonable expectation of privacy. Generally while. "in public", there is no "reasonable expectation of privacy".
Agreed- ALWAYS record, from the moment you strap one on, until you put it away.
There are several good, inexpensive recorders that will record continuously for 20-30 hours with good quality. Look for one with built in USB capability; it makes it much easier to save your recordings to a computer.
I save them all, including the uneventful ones. Perhaps I'm a touch over cautious, some might say paranoid, BUT, nothing shows that nothing happened like a recording of a normal conversation. I'm always a little concerned that someone may 'embellish' an otherwise simple encounter to further some agenda.
Essentially, you may record any conversation you are party to, even if you are not an active participant. Read up on the laws here:
http://www.citmedialaw.org/legal-guide/michigan-recording-lawThere are a number of threads on preferred recorders on various open carry websites. Here's one example:
http://forum.opencarry.org/forums/showthread.php?44913-Voice-Recorder&highlight=recorderAnd, above all, welcome to MOC!
