Ian Burrell: Undercover journalism: does the end always justify the means?

A battle-hardened old hack like Kelvin MacKenzie has observed the passing of many media storm clouds over the years but is convinced that what he's seeing now is different. "Journalism, in a strange way, is under attack in a way that I haven't seen it under attack in the last 30-odd years," he says.

Big scoops are increasingly being subjected to criticism. The Daily Telegraph, having exposed the real views of the Business Secretary Vince Cable, finds itself being investigated by the Press Complaints Commission over its use of undercover reporting. Julian Assange's Wiki- Leaks, having published thousands of secret US government documents concerning the wars in Afghanistan and Iraq, found itself criticised by Amnesty International for its lack of discretion. The News of the World, which for years has engaged in subterfuge, finds itself engulfed by legal claims over its alleged hacking of mobile phones. The paper is still in shock after its exposé of Formula 1 chief Max Mosley's predilection for sado-masochism resulted in a fine over its intrusive reporting methods.

MacKenzie believes there has been a shift in the way big exposés are received. "Everytime anything of a discomfiting nature is revealed now, the first thing that people shout out is 'foul'," he says. "What's constant now is that the revelation is not the story, the story is the method of the revelation, and that to me is a change for the worst."

The former editor of The Sun praises as "a triumph of reporting" the Telegraph's story that Mr Cable told its reporters that "I've declared war with [Rupert] Murdoch". Last week the president of the Liberal Democrats, Tim Farron, asked the PCC to investigate the paper's use of "clandestine fishing expeditions" at the surgeries of its MPs.

With newspaper organisations – and indeed ordinary members of the public – broadcasting on websites, Iain Overton, editor of The Bureau of Investigative Journalism, is worried that undercover reporting will increasingly be used without justification and outside of the regulation of broadcasting watchdog Ofcom. "The concern is that the print media think that all you have to do is go in, masquerade as somebody else, get somebody to say a cheap comment and then you have an easy headline. That isn't how the broadcast media has ever operated," he says. "To even consider undercover filming you have to have a very strong public interest and prima facie evidence."

Michael Williams, head of ethics in the Journalism School at the University of Central Lancashire, is convinced that the Telegraph's reporting was entirely justified. "When we talk about what are the core functions of journalism, one of them is to expose deceit in the people who are governing you. This story succeeded absolutely in that."

A former Fleet Street executive, Williams said the Telegraph used methods deployed by red-top newspapers for decades. "What's caused a frisson is that it has been taken up by the posh papers and taken into the seats of power. It was fundamentally no different from what [News of the World investigations editor] Mazher Mahmood does."

Stryker McGuire arrived in Britain in 1996 to work for Newsweek, for which he is still a contributing editor. "When I came here in 1996 I immediately recognised that the tabloids and the broadsheets basically played by different rules. Tabloids could buy stories, broadsheets didn't. That was the clearest rule of all," he says. "Over time there has simply been a blurring of the lines."

McGuire, editor of LSE Research at the London School of Economics, says the Telegraph's decision to pay for details of MPs' expenses was part of that process. "Under American journalism standards it couldn't have been done that way," he notes, though the issue was so important "it was better to have the story out there".

He regards as "frankly much more questionable" the stories gleaned by undercover reporters posing as constituents. "That was justified on the grounds that the individuals in private were saying things that they were not saying in public. I don't think that myself, I don't think that's worth the sacrifice that the media organisation makes by doing that."

The broadcaster and former tabloid journalist Nick Ferrari says his listeners have little sympathy with politicians who claim their privacy has been impinged on. "The simple message is don't say it and you won't be reported," he says. "Instead of moaning, politicians should look at the reports that say they're held in lower public esteem than estate agents and tabloid journalists."

According to MacKenzie, that's just where journalists ought to be. "The public expect them to be low-lifes," he says. "At the bottom of that ladder is the journalist because he or she has to do the most uncomfortable thing of revealing what people are thinking and doing. Carry on hunting, that would be my message."