Two activists have won their case against policing of the G20 protests, as the High Court ruled police containment was "not justified".
The judges upheld Hannah McClure and Josh Moos's case that police used "violence" to control the Camp for Climate Action in London in April 2009.
There was "no reasonable" justification for "kettling" but police did not unlawfully try to clear the camp.
The Metropolitan Police said it would appeal against the court's judgement.
In response to this, Frances Wright, from the climate camp's legal team, said: "It is outrageous that public money is continuing to be used to defend the kettling of the climate camp for five hours.
"The police lost the argument in the media and public confidence dropped, two parliamentary committees were critical and now the court has agreed."
John Halford, counsel for the demonstrators, said: "The court has roundly condemned the unlawful and oppressive police response, exposing it as unacceptable in a democratic society."
The Met's decision to push protesters at the Bishopsgate camp was "not necessary or proportionate", the judges decided.
Three activists at the camp had challenged the legality of police using riot shields to land blows on protesters at the G20 demonstrations, known as "shield strikes".
Chris Abbott's case was dropped because he could not get legal aid, his lawyers said.
Sir Anthony May, the president of the Queen's Bench Division, and Mr Justice Sweeney rejected the complaint that the Met decided unlawfully to clear the climate camp before it was due to end.
Met officers "kettled" demonstrators for more than four hours on 1 April, the same day newspaper vendor Ian Tomlinson died after being pushed down by a police officer in Royal Exchange.
Ruling in the case, the judges said: "There was at 7.07pm no reasonably apprehended breach of the peace, imminent or otherwise, within the Climate Camp itself sufficient to justify containment."
But the court heard that later in the evening there was a risk and police reaction was appropriate.
There had already been incidents at the Bishopsgate camp where bottles and coins and other items were thrown at the police lines, but the protest had been largely peaceful, the court heard.
"When the Royal Exchange protesters were dispersing from 7.25pm there was clearly a risk that some of them might head for the Climate Camp and the police were right to anticipate the risk and take appropriate steps to deal with it, if it materialised," the judges said.
They said the Met's decision to push protesters 15-person deep was not needed.
"We think that the police were right to have an eye to infiltration from Great St Helens Street and the street or alleyway opposite, but we are not persuaded that the pushing operation of a 15-person deep crowd to move them approximately 20-30m to the north and beyond these side roads was reasonably necessary.
"It follows that, in our judgement, the pushing operation from the south was not necessary or proportionate."
On the use of shields the judges ruled: "The policy and training about the use of shields as it came over to us in the evidence appeared to be insufficient for individual circumstances.
"There needed to be clear-cut instructions as to whether shield strikes were ever justified, and, if so, when."
The judges said the Met had a duty to clear the road, "by force if necessary", but added: "If there were individual occasions when the force used may have been excessive, that is a matter for individual complaint, not for these judicial review proceedings."
A Met statement said the judgement recognised police concerns about the possibility of a breach of peace at the camp and officers believed "the Bishopsgate containment prevented further scenes of violence and criminal damage occurring on 1 April 2009".
The force said: "We have rigorously defended the claims against the MPS because at the heart of this case lies a vital public order policing tactic that prevents disorder and protects the public.
"It should be noted that the judgement relates to the individual circumstances of 1 April 2009 and not the use of containment at other events.
"Where necessary we will continue to use containment as a last resort to prevent serious disorder and violence.
"We will be appealing the Administrative Court's finding that the containment and pushing operations on the 1 April 2009 in Bishopsgate were not lawful."