My department allows strikes but you have to be aware of liability. I've never had to use a closed fist. What has worked best for me is a set of concepts from lama style training which emphasize "core" and gross motor skills which segue from strikes to grappling/joint locking. This way you don't have to withdraw your hand after a strike--the same movement carries on into a takedown or joint lock. There is none of that silly grabbing for the wrist thing.
Choy Li Fut has some very good palm methods as well. Generally, at least one limb is controlled or isolated when the palm strike is delivered. This sort of tactic has the advantage of appearing defensive and part of a normal battle for compliance if you are on camera.
Beware of the "heart pump." Prosecutors are well aware of the nasty history of this technique in law enforcement and your department would probably lose the legal battle.
Be safe.
"Look, I'm only doing me job. I have to show you how to defend yourself against fresh fruit."
For it breeds great perfection, if the practise be harder then the use. Sir Francis Bacon
the world has a surplus of self centered sh1twh0res, so anyone who extends compassion to a stranger with sincerity is alright in my book. also people who fondle road kill. those guys is ok too. GunnedDownAtrocity