Banning the press from reporting a notorious criminal's alleged activities would have a chilling effect on attempts to expose an underworld of drugs and murder, the High Court heard today.
Lawyers for the Sunday World also argued that Brendan Conway should be denied an injunction because he is allegedly associated with dissident republicans.
The 39-year-old north Belfast man claims the newspaper has subjected him to a sensationalist campaign of vilification and harassment.
Articles which alleged he is a Real IRA boss and police informant involved in a killing came close to using hate language, a judge was told.
Mr Conway emphatically denies all of the claims made about him in the newspaper.
His barrister contended that the reports are false and have put his life in danger.
Police have issued two threat warnings about a planned gun attack on him since the first of four articles was published last October.
Mr Conway, who was in court, has also been assaulted twice and abused in the street as being "a tout", the court heard.
Brian Fee QC said: "He has indicated that he has effectively had to go into hiding."
The injunction being sought is to restrain the Sunday World from publishing any more allegations of serious criminal behaviour about him.
The court heard it has reported his alleged involvement in the murder of Kevin Kearney in north Belfast last October.
He was questioned but never charged in connection with the killing, Mr Justice Gillen was told.
With the newspaper having described him as an associate of Lurgan republican Colin Duffy, a further allegation was that he supplied bugged cars to dissident leaders in his role as a police informant.
"The articles amount to an orchestrated, repetitive and escalating campaign against Mr Conway," his counsel said.
As well as claiming harassment, he contended the newspaper is guilty of malicious falsehood and misuse of private information.
Libel proceedings have also been issued.
Accepting that an injunction would impact on the Sunday World's freedom of expression rights, Mr Fee argued that these were trumped by right to life entitlements.
He said refusing the application could result in a "potential catastrophe" for his client.
He described Mr Conway as "a man with republican views and with a modest criminal record".
Although the plaintiff has a conviction for robbery, his barrister accused the Sunday World of wrongly reporting he had a record for tiger kidnapping.
But counsel for the newspaper, which is being supported in the action by the BBC, UTV and Belfast Telegraph, insisted the conviction related to taking £230,000 from an under-threat Ulster Bank employee.
Brett Lockhart QC argued: "We are dealing here with a notorious criminal who is very strongly associated and identified with notorious dissident republicans who have been involved in the most serious of crimes imaginable."
He continued: "If granted, (the injunction) would genuinely have a chilling effect on the press' ability to uncover serious criminal activity and the various individuals (involved), which is indisputably in the public interest."
Mr Lockhart distanced the proceedings from others dealing with "adultery, tittle-tattle or the private lives of celebrities".
"This is a case which reveals a virtual underworld which involves drugs, which involves murder, which involves dissident republican activity," he told the court.
He stressed that the Sunday World reporter who wrote the stories had carried out a 15-month award-winning investigation.
She received death threats and had to leave the country because of her work, the court heard.
Contending that the newspaper was "revealing the internecine warfare going on between factions in certain parts of Belfast", the barrister said Mr Conway had voluntarily chosen to become a spokesman for republican prisoners and publicly associate himself with Colin Duffy.
Challenged by the judge on the claim that the articles should be stopped because they are putting the plaintiff at risk, Mr Lockhart replied: "His life is already in danger by virtue of the activities he has involved himself in."
The hearing continues.