100% you get away with it....I speak from experience, lol.........watched a dude with a "slim jim" tool trying to break into my truck at a lake in the Okanagan area......I ran up and bounced his head/face off the top of my door....instant KO.....had a schedule to keep so I called the cops, told them what happened and where, etc, etc and just left dude laying there when I drove off (2 other people were there as well and stayed and watched from a distance, but no idea what came of it).......cops took my info in case they needed to contact me further and I never heard from them on it again, lol (2010 fall).....not sure if they even came out and got the guy or not as it was a fair ways away from any detachment......would I do the same if I seen it happen again.....absolutely......probably would even still do it even if it was somebody else's vehicle.......of course only if I was sure they were breaking in to steal something rather than an owner who locked their keys in or similar, lol
Anyways, long story short, it didnt even come down to my word against his as I told the cops flat out exactly what happened and that I KO'd the guy and why and the cop literally laughed when I told him what I did, lol.......im sure technically the guy may have been able to file charges but wasn't going to happen considering the circumstances, lol.
HOWEVER....I dont recommend this type of vigilante justice unless you are willing to take the risk or are confident enough in yourself to handle the situation or any situation that could arise out of it!