Probably irrelevant but here in South Oz, if I am off duty and assaulted (just as a person in a bar for instance) then it is straight assault. If I was able to control the situation I might identify myself as a Police Officer, and detain the male until uniforms arrive, however it depends on a lot of factors.
If I was at a bar and a guy was acting stupid or whatever, and I identified myself as a Police Officer and told him to shut up (not that I would do that off duty) then he assaulted me, then it would most likely be Assault Police.
As soon as I identify myself as Police and act in an offical capacity, I have effectively recalled myself to duty.
Keep in mind that here, Assault Police is a minor offence as some weak judge once came up with the idea that Police should expect to be assaulted so therefeore it goes with the territory.
Assault Police is not charged as much as it used to be as it is treated lightly by the court and some time ago they changed our arrest procedure to incorporate the taking of DNA for certain offences, assault Police being one. When that came in less charges of assault police were laid. Not that I am saying that cops couldn't be bothered charging an offence (which was usually a second or third offence anyway) when it just meant more work for the cop and no real impact on the crook. also we got OC spray and that helped drop assaults on police, as they don't get close enough to hit me now.
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