The High Court yesterday shot down a Competition Authority ruling that it could "veto" lawyers chosen to represent any parties it is investigating.

In autumn 2004, the authority declared that it would refuse to deal with lawyers representing organisations or people it was investigating, where it believed that their representatives had a conflict of interest.

Yesterday, the High Court upheld a Law Society challenge against the ruling, which was brought on the on the basis that the authority's statement breached the constitutional right to legal representation.

Mr Justice Iartfhlaith O'Neill said that anyone facing an investigation or tribunal had the right to freely select lawyers willing to represent them, from the pool of lawyers available to take instructions.

He added that the authority's ruling would infringe people's right to legal representation.

However, the judge rejected an argument by the Law Society that where the Competition Authority was concerned about a case where solicitors had a conflict of interest, it should complain to the society, which regulates solicitors.

The judge said that even if this avenue was open to the authority, it could result in delaying its investigation.

When the authority made the ruling in autumn of 2004, it said it was particularly concerned about protecting its immunity programme.

This is designed to give individuals who have been involved in price fixing and other organised breaches of competition law immunity from prosecution where they co-operate with authority investigations.

In 2004, authority director, Terry Calvani, said that this could be damaged if the authority had to deal with lawyers who were simultaneously acting for parties who were, and were not, co-operating with it on the same investigation. However, the judge said yesterday that a lawyer acting for two different parties under investigation by the authority would not necessarily face a conflict of interest.

In his ruling he pointed out that in that situation, a lawyer could not direct one of his or her clients not to give evidence that would incriminate another of their clients.

He also stated that the authority should contact all parties connected with any of its investigations and inform them of the immunity programme, and how they can avail of it.

Deputy Law Society director, Mary Keane, yesterday welcomed the court's ruling.

"The right to be represented by a lawyer of your choice is a fundamental tenet of any democracy. The authority's attempt to restrict that freedom of choice was an alarming move," Ms Keane added.

She said: "the public interest has been well served by today's decision."