Ms Moreno, from Barry, Vale of Glamorgan, had her right leg amputated below the knee after being hit when the car left the road on the island of Zakynthos in May 2011.
The Motor Insurers’ Bureau (MIB), which compensates victims of uninsured drivers, has admitted liability but contends damages should be calculated according to Greek law.
It argues that damages in uninsured driver cases should be assessed according to the law in the country where the accident happened in the same way as they would be if the accident was caused by an insured driver.
Five Supreme Court justices agreed and unanimously allowed an MIB appeal against an April 2015 ruling by High Court judge Mr Justice Gilbart that the law of England and Wales should be applied.
The MIB is handling Ms Moreno’s claim on behalf of its Greek equivalent, the Greek Guarantee Fund (GGF), under EU law provisions which mean a victim of an accident abroad does not have to pursue a claim directly with a foreign organisation.
Lord Mance said Ms Moreno was walking along the verge of a road when she was struck from behind by a vehicle driven by Kristina Beqiri, who neither had a valid driving licence nor, it appeared, any insurance. Beqiri admitted responsibility for the accident.
The judge said: “Sadly, Ms Moreno suffered very serious injuries, which included loss of her right leg, requiring her to use a wheelchair, continuing pain and psychological reaction, as well as loss of earnings.”
The judge added: “Ms Moreno’s concern is that Greek law would yield a lesser measure of compensation than English law.”
But Lord Mance pointed out that UK drivers who had similar unfortunate accidents at the hands of uninsured drivers in other EU countries could fare better than under English law.
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