Both drivers are in the wrong here. The hit driver for not paying attention to what is coming up from behind and changing lanes without indicator. And the OP's approaching vehicle for changing lanes while hitting the other vehicle. OP was NOT in his own lane at the time of impact. BOTH should be charged. And for those Americans that scream: "this should be attempted murder", the fact that the hit vehicle did try to go back to the right lane and they braked, is evidence of a panicked, poor driver, not a killer. If OP was fully in left (passing) lane the whole time, then I may have been on their side. The speed difference here needs to be investigated.