A black Volvo sedan sits in a ditch in a snowy field. The front end of the car is badly smashed in and the driver side door is open.

Some doctors are being accused of offering shoddy or biased evidence in cases where big insurance companies are looking to block or reduce payouts for people hurt in car crashes. Yet they face no penalties or sanctions for their flawed reports, and nothing is stopping them from appearing in court again, says an expert.