Relatives of Mark Saunders, the barrister shot dead by police, welcomed a ruling by a High Court judge yesterday that said allowing officers to confer with each other during inquiries into police conduct raises a risk of collusion.

However, although Mr Justice Underhill criticised the established practice, he dismissed the Saunders family’s claim that an investigation into how police killed the barrister was unlawful.

In a landmark legal decision, the judge said that the “opportunity for collusion was institutionalised” in the system for investigating fatal shootings.

Mr Saunders, 32, a divorce lawyer, died in May when seven officers fired 11 rounds at him, ending a stand-off at his flat in Chelsea, West London. Eleven firearms officers conferred with each other before producing their accounts of the incident, a practice that Mr Saunders’s family argued was unlawful under the European Convention on Human Rights.

Police have been able to discuss cases with each other for more than 50 years and the practice is prescribed in the police firearms manual. But it has been widely criticised since the shootings in London of Harry Stanley in 1999 and Jean Charles de Menezes in 2005.

Mr Justice Underhill said there was a “real risk” that officers’ recollections would be “contaminated” after talking to their colleagues. The courts should be very wary of “a general practice under which officers who are key witnesses in an investigation are expressly permitted to collaborate in the production of their statements. The opportunity for collusion is, so to speak, institutionalised.”

However, the judge held that the Independent Police Complaints Commission’s inquiry into Mr Saunders’s death was not unlawful, as forcing officers not to confer would create “a very serious risk of individual officers refusing to provide a statement”. He added: “A departure from the long-established practice of collaboration would encourage a perception that they were, whatever assurances were given, suspects and not witnesses.”

Charlotte Saunders, 26, Mr Saunders’s sister, is appealing against the decision and said that she would lobby the Home Secretary for a change in the law. “I brought these proceedings because I was concerned that the police officers who shot Mark were allowed to confer before giving their statements to the IPCC,” she said. “It is encouraging that the judge agrees that this practice might be unlawful and that he decided that the opportunity for collusion is ‘institutionalised’.”

Police chiefs are considering changing the police manual to ban collaboration.

Nick Hardwick, the chairman of the police complaints commission, welcomed the judgment. “It supports the calls the IPCC has been making for changes to the way officers confer to write their notes after a fatal shooting, which does not provide best evidence or secure public confidence,” he said.

The Police Federation said: “Conferring before making notes is a long-accepted practice which is intended to achieve best evidence.”

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