The rights of Sun journalists were "unquestionably violated" when the Metropolitan Police secretly obtained their phone records, the Investigatory Powers Tribunal has heard.
The communications data of three journalists and the newspaper's newsdesk were grabbed under the Regulation of Investigatory Powers Act as part of the force's probe into the Plebgate scandal.
The Tribunal heard today that the Met Police obtained a week's worth of phone records from political editor Tom Newton Dunn, crime reporter Anthony France and political correspondent Craig Woodhouse. GPRS data was also obtained against their telecoms records.
The Met also obtained records from Sun newsdesk numbers to find sources.
The Met revealed that it had obtained the phone records of Newton Dunn and the newsdesk in September last year when it published the Operation Alice Plebgate investigation closing report. The fact France and Woodhouse were also targeted emerged "through admissions by the [Met] in these proceedings".
Gavin Millar QC, for the journalists, argued that the Met should have sought to use the Police and Criminal Evidence Act or the Norwich Pharmacal jurisdiction – which allows employers to ask the High Court for source identification where an employee is believed to have breached confidentiality – instead of using "covert powers under RIPA".
"It does not appear that either of these less drastic remedies, which would have allowed the judge to receive evidence and representations from the complainants, were even considered before the communications data was obtained under RIPA," Millar's skeleton argument said.
"Nor was there a careful scrutiny of the facts and an application of the relevant legal principles as required under Article 10 [of the Human Rights Act]. This is guaranteed where judges rather than police officers take the decisions. If there had been, it would have been clear that on each occasion the measure sought (the covert obtaining of the data to identify a source) was not justifiable."
The submission said that no explanation has been provided to explain why PACE and Norwich Pharmacal was not considered, "which is presumably because there is no good explanation".
He said the failure to do so "had disastrous consequences" and that if the case had gone to court, News Group Newspapers could have made clear to the police that the confidential source of the story was Newton Dunn's alone and that therefore the records of France and Woodhouse should not have been taken.
Evidence is being analysed by the Investigatory Powers Tribunal – which considers complaints about the way public authorities use covert techniques – at a hearing due to end tomorrow.
The litigation is centred on police enquiries after Conservative MP Andrew Mitchell was accused of swearing at police in Downing Street. Complaints that the then Government chief whip had been abusive first emerged in The Sun in September 2012.
Journalists' lawyers say a central issue is whether detectives' ''recourse'' to ''the disputed RIPA powers'' in order to identify ''confidential sources'' was necessary.
Police deny wrongdoing and say complaints should be dismissed.
Jeremy Johnson QC, for the Metropolitan Police, said: "It was reasonably suspected that there might be a criminal conspiracy by police officers to smear Mr Mitchell and thereby cause his resignation and destabilise the government, with the intention of promoting opposition to government cuts to the police service.
"In the course of the ensuing criminal investigation, under the independent supervision of the Independent Police Complaints Commission, the Metropolitan Police Service obtained call data which was likely to (and was) of significant assistance in furthering the investigation (ultimately establishing that there was no such conspiracy…)."
He said it had been necessary and proportionate to obtain call data because police were investigating a suspected criminal offence.
And he said call data had been obtained in "accordance" with RIPA. He said the claims should be dismissed.
Lawyers said judges could award compensation if they ruled in favour of journalists and News Group.