A barrister for the Northern Ireland Civil Rights Association said yesterday the failure of the British army to divulge its plans for an arrest operation to the march organisers contributed to the shooting on Bloody Sunday by paratroopers of 27 civilians, 13 of whom died.
Sir Louis Blom-Cooper QC told the inquiry into the January 30th, 1972, killings that the communication between the march organisers and those responsible for its policing was an essential ingredient of any reliable risk assessment and the "failure to communicate was primarily, if not exclusively, the fault on the part of the army".
The route of the civil rights demonstration was to have taken the marchers from the Creggan area of Derry into the city centre at Guildhall Square.
However, the march was diverted into the Bogside when the British army erected barriers blocking the route to the city centre.
Sir Louis said the NICRA was fully entitled to take the view expressed by the city's most senior police officer, Chief Supt Frank Lagan, that the safest way to police the march was to allow it to proceed unimpeded to the Guildhall for a lawful meeting to take place.
He said Chief Supt Lagan believed that by allowing the marchers to enter the Guildhall Square, the police and the army could have photographed any confrontations and could have subsequently arrested and prosecuted rioters.
"This would have had the added benefit of minimising the risk of confrontation between the marchers and the security forces," he said.
In his final submission, Sir Louis told the inquiry, chaired by Lord Saville of Newdigate, that the absence of any communication by the army outside of military circles of its plans for policing the march, including specifically its plans for dealing with any rioting, was a failure to act appropriately.
"The tragedy of Bloody Sunday was initially and consequentially the failure of the army to communicate to the organisers of the march that it was preventing the march from going to the Guildhall.
"The result was, at least, confusion about the policing of the demonstration and the military attitude to the nature of a civil rights march," Sir Louis said.
Meanwhile, Mr Barra McGrory, the solicitor who represents Sinn Féin MP Mr Martin McGuinness, who was the Provisional IRA's second in command in Derry on Bloody Sunday, said that intelligence material which alleged that his client had fired a shot on the day was unreliable.
Mr McGrory said: "I would simply make the general observation in relation to intelligence material, that perhaps the experience in recent weeks and months of the possible unreliability of intelligence in Iraq as to weapons of mass destruction, the existence of them or otherwise, might show the inherent unreliability of intelligence and must be always borne in mind by the tribunal."
The inquiry continues.