If you hit another vehicle due to what you believe to be unlawful or reckless behavior on their part, the first thing you should do, if possible, is to contact law enforcement for a report. A documented report on behalf of law enforcement in addition to photos and medical records of injuries you incurred will help prove that although your vehicle stuck theirs, it was their actions that caused the accident. Without a n-fault judgement on your end, you could be left open to covering the cost of your medical bills and automobile repairs.