A student has brought a rare High Court libel jury action over claims about his role in the anti education cuts demonstration which turned into a riot.
Luke Cooper's reputation had been "as badly trashed" as the capital's Millbank Tower during the November 2010 march, William McCormick QC told Mr Justice Eady and the jury in London.
Cooper, 27, who is studying for a PhD in international relations at the University of Sussex, wants damages and an injunction from Associated Newspapers, which denies libel.
McCormick said that an Evening Standard (which was then owned by Associated) front page article meant that Cooper was a ringleader, and planned with others in advance to hijack a peaceful march and turn it into a riot.
The accompanying out-of-context picture, taken from a photo sharing website and showing Cooper at a social event in a pub a couple of years earlier, gave the impression of a man "smiling joyously at the havoc wreaked".
A subsequent Daily Mail story used the same photo and portrayed Mr Cooper as one of the "hard core" who organised the riot at the Conservative Party's headquarters.
Counsel said that Cooper, a socialist who was not afraid to speak out and saw nothing wrong with peaceful protest or direct action, had been grossly libelled.
He was aware there were plans for some form of protest on the 50,000-strong march as he had seen emails to that effect, but had not responded to them and had no part in planning it.
He took no part in the violence or property damage at Millbank, where a fire extinguisher was thrown from the roof, but simply milled around outside with thousands of other students to register their protest.
He was willingly interviewed by an Evening Standard journalist, but claimed that some of what he said was inaccurately reported or omitted.
Mr McCormick said that, after the coverage, Cooper received attacking emails from people who sought him out on the internet, and faced the stress of the launch of disciplinary proceedings at the university which came to nothing.
He told the jury: "It is a myth that libel is just about money, It is not. It is about reputation.
"Luke Cooper's reputation has effectively been as badly trashed as Millbank Tower on November 10 2010.
"He has been accused of being responsible for a serious piece of public disorder - effectively seeking to use others as his pawns to achieve his political aims - and that is severely damaging to his reputation."
Opening the week-long case, McCormick told the jury that they might be a "small footnote in legal history" as libel trials were rare and those involving jurors almost extinct - the last one having taken place three years ago.
Cross-examined by Adrienne Page QC, for the newspapers, Cooper said he attended the demonstration partly as an activist for Revolution - the socialist youth organisation he was a member of - and partly to support a demonstration in which he believed very strongly.
He said he was handing out a Revolution fanzine at the back of the crowd and was not that aware of what was going on, although he understood that some Revolution members were in the first wave to enter Millbank and hung a large banner from its roof.
He denied approaching the Evening Standard journalist and telling him he could speak on behalf of the group.
He said the great majority of demonstrators were not committing criminal acts and he did not condone the actions of the minority.
The case against Associated and Evening Standard Ltd, which also denies libel, was adjourned until tomorrow.