So... what's a cop supposed to do?
A cop must arrest/restrain a potentially dangerous guy who is uncooperative. The guy can be quite strong, or he can carry a concealed weapon.
So, what he's supposed to do?
This is the big elephant in the room, and for some reason nobody is talking about it. What's the right protocol? Guns? dismissed, if the cop can't shoot, once that becomes clear this is the most likely outcome https://www.youtube.com/watch?v=DGIpAweGQGQ. Taser? dismissed, it's non lethal, but in some rare cases and health conditions, it could be lethal. Knee on the neck? the same.
Then what?
The only solution I can find is the cop asking the suspect to cooperate. If that's not the case, the cop should tell whoever called him 'sorry, mate, best wishes' and walk away.
Discuss.
EDIT
Answers that actually have proposed something specific until now:
■ Use a taser.
■ Use a spray.
■ Check first that nobody is recording.
■ Tranquilizer darts.
A taser can be lethal in some rare cases (heart condition). A spray can be very dangerous too in some rare cases (respiratory problems).
Tranquilizer darts can be quite dangerous and lethal if you don't the exact right dosage: https://www.quora.com/Why-don-t-law-enforcement-officers-use-tranquilizer-guns-when-they-re-shooting-someone-as-a-way-to-control-the-situation-without-definite-consequences?share=1
What remains is to check that nobody is recording. So, at the end of the day, that's what cops have. If I was a cop, I would walk away and wouldn't get into trouble.