over here being liverpool - north wales corridor - wouldn't even get a slap on the wrist for laying someone out cold for showing bad manners or total disrespect and the cops know that so they don't do anything about it.
failure to shake their hand implies that they've got really bad germs n diseases n stuff - totally disrespectful to them and that's all that's needed (actually takes a lot less than that sometimes) unless you look at them wrong and then well yup............ pine box.........
and chances are that you wouldn't get done for that either --- it's part of the personal safety laws - "your honour he drew his hand back as if to hit me so i got in first to protect myself your honour"
slap on the wrist and maybe a small fine and told to behave from now on
you just gotta love english/welsh justice