Family sues over alleged MMR link to autism
The test case, which could open the floodgates to hundreds of similar actions, is set to reignite the fierce debate over the safety of the mumps, measles and rubella jab.
The family, from Glasgow, is among nine suing the government in a joint action. They cannot be identified for legal reasons.
Legal experts said that if the challenge is successful, each child could receive 5 million in compensation.
The parents are seeking a judicial review at the Court of Appeal over a decision by the Legal Services Commission to withdraw legal aid. Denied financial assistance, they have been forced to bring the case to court themselves.
Arguments over the triple vaccine have divided families and even elements of the medical fraternity, both at home and abroad.
Dr Andrew Wakefield first spoke of the possible link between autism and MMR back in 1998, but since then several studies have concluded that the jab is not linked to such disorders.
Jackie Fletcher, the founder of JABS, a "support group for vaccine-damaged children", has campaigned for more than a decade on behalf of hundreds of families affected by autism.
She said today's case was a final attempt to access justice for children in the UK courts. If unsuccessful, the parents will go to the European Court of Human Rights, she said.
A spokeswoman for the Department of Health insisted MMR was safe and urged parents to have their children vaccinated.