After an accident, it is the job of the insurance company claims adjuster to allocate the relative degrees of fault based on the conditions surrounding the accident. There is no magic formula mathematical formula for determining percentages of fault in accident injuries. You and the claims adjuster will work out and arrive at some arrangement as to what, if any, your allocated fault is. Here is where an experienced personal injury lawyer can prove useful.
He or she will know how to assess the accident and recommend for the lowest percentage of wrong doing on your part. If you and the insurance adjuster reach an impasse, a court of law is ultimately your next step to deal with the issue of fault.