[pieater]

Last year I was assaulted in Berlin by a Canadian.

Now that sounds like a night out. Hats off. Hope it wasn't too grim. Two ways forward with this:

1, Bring a civil action against the aggressor. For this to yield significant amounts of compensation, your injuries will have to have left permanent scars and / or have led you to financial loss (e.g. loss of earnings).
If this is the case, go and see your local lawyers, or PM me.

2, You could contact the Canadian law enforcement agencies and make a complaint. This would depend on their willingness to take this on. I'm betting this won't be great, but you never know.

Martin