Rule of thumb, he come into your lane and didn't squeeze in in
time, his fault. Physically would be you bang his side. If you bang
his rear, you are at fault, for failing to keep a safety distance
or being unable to guide correctly. So where did you bang?
He will always say you are at fault and vi versa. So just stat your
own accord, and his his own into the accident report form and let
the inspectors solve it out. I kanna once, I would say it is
clearing his fault (he filtering left into my lane). Anyway, after
that I always drive defensively (like as and when they will just
shoot out, always give way to those who signal whenever possible).
My little car can't take another shock! 
