- SmithKline Beecham has asked the High Court to throw out a ruling against it by advertising watchdogs because of what it claims was bias by an "independent" expert.
Dental specialist Dr Steve Creanor had already publicly criticised advertising for the company's Ribena Toothkind children's drink before he was called to give impartial advice to the Advertising Standards Authority.
As a result, his views "infected" the ASA's decision to ban what it said were unsubstantiated advertising claims for the product, the court was told.
The legal battle centres on whether or not SKB has the right to claim that Ribena Toothkind "does not encourage tooth decay".
The company has invested £19 million in the development of Ribena Toothkind, launched two years ago in an attempt to rehabilitate the Ribena brand after widespread criticisms of its effect on children's teeth.
The application for a judicial review is the first to go to court since the setting up of an independent appeals system against ASA decisions which failed to resolve the dispute.
SKB said Creanor, senior lecturer in oral sciences at Glasgow University's dental school, had already been critical in print of a Ribena Toothkind poster depicting bottles of product as bristles on a toothbrush.
He claimed it to be "inappropriate" and not putting across the message that the British Dental Association, which has accredited the product, would have wanted.
SKB claims the ASA had paid insufficient regard to the backing of Ribena Toothkind by the BDA's panel of distinguished scientists as well as other experts from Leeds University who found the product posed "no significant risk" to tooth enamel.
David Pannick QC, representing SmithKline, told Mr Justice Hunt: "We have been found guilty of misleading the public. We say that is a complaint which cannot sensibly be substantiated when a large number of independent experts take the view that the advertising claim was a perfectly proper one based on the scientific evidence."
Charles Flint QC, for the ASA, claimed Creanor had expressed a view about the advertising that any responsible expert might take and that two of the four experts of the BDA's panel had been given research grants by SKB.
He described Creanor's remarks as "preliminary only, a matter of first impression and did not preclude him from fairly judging the evidence."
He added: "The ASA was entitled to take the view that the BDA had not approved the blanket claim that the product did not encourage tooth decay".
The judge is expected to deliver his verdict early in the new year.