Churchill insurance are appealing against a multi-million pound compensation claim by a teenager left with brain damage in a car accident on the grounds she was not wearing a high-visibility jacket.
Bethany Probert was 13 when she was hit by a car as she walked home from a nearby riding school in Silverstone, Northamptonshire, at around 4.30pm in December 2009.
Now 16, she suffered traumatic brain damage and has a range of health problems including physical disabilities and memory loss, her mother Jo Twyman said.
The case reached the High Court last July where a judge cleared Miss Probert of any contributory negligence and held the driver's insurers fully liable, meaning she would receive full compensation of between £3 and £5 million.
But now the Court of Appeal has given insurers Churchill permission to appeal against the decision, putting at risk the compensation which would cover the cost of adapting a new home for the teenager's needs and her ongoing care.
Bethany's solicitor Richard Langton, of Slater & Gordon, said: "One of the key issues they say is that she should have been wearing a high-vis jacket but I don't know anyone who owns one, never mind wears one. It's a very disappointing decision by the judge to approve this appeal.
"This is the first case I know of its kind on the question of an accident victim's culpability for walking on the road at night involving a child."
The driver moved aside to make way for oncoming vehicles on the night of the incident but hit Miss Probert without seeing her in the darkness. He stopped and found her in a nearby ditch.
Miss Probert's mother, Ms Twyman, 51, said: "Since the accident, Beth has suffered a number of problems, including memory loss and seizures and has to use a wheelchair at times.
"I'm yet to see a teenager wearing a high-vis jacket when I'm driving around at night. We just want all this to be over."
In a statement, Churchill said: "While we accept that our insured was liable in part for the accident, we are appealing [against] the decision that he was entirely to blame."