The four, from Greenpeace groups in Germany, Switzerland, Norway and Spain, have had to promise that they will return to Copenhagen for a trial later this year. They will be accompanied by a further five protesters who took part in the action, the details of which were passed to police by Greenpeace this week as part of the conditions of release. The nine have been charged with impersonating police officers, trespass, and falsifying documents.
On Thursday 17 December, the three-car convoy of activists drove unchallenged through several checkpoints and into the palace compound. Two of the activists, dressed in black tie and posing as the representatives of an imaginary country called Mother Earth, walked along the red carpet just behind the US secretary of state, Hillary Clinton, and in front of the media unfurled banners saying: "Politicians talk, leaders act".
Today it emerged how simple it was to outwit the Danish police and pose as a head of state, his "wife" and a security detail. One of the car number plates included the numbers "007" - a reference to James Bond. The protesters put police lights - bought for £6 on the internet - on top of their two security cars.
"It was arranged in a hurry. Once we heard about the dinner we generated some ideas but in the end we had to run to make it happen. We knew what they would look for, like the number plates. But it is amazing what a good suit will do," said Joris Thijssen, from Holland, one of the four.
"We did it because at the time there was only 24 hours left for world leaders to reach a global agreement. It was like a building was burning and we wanted to put out the fire. Yes we did something a bit naughty but we felt it was proportionate. We did something naughty to try to stopclimate change becoming climate chaos. The judge needs to trade off the act we did against the bigger crime we were trying to prevent. We thought it justified," he said.
Today Thijssen pleaded for the release of 12 other protesters from across Europe who have also been held in a Copenhagen prison since the summit. "I hope the Danish government gets its sense back. They are still under investigation. Anyone who just exercised their right to peaceful protest should be released," he said.
The 12 others being held in prison wrote earlier this week: "We are detained with evidently absurd accusations about either violences that actually did not take place or conspiracies and organising of law-breaking actions. We do not feel guilty for having shown, together with thousands, the reclamation of the independence of our lives from profit's rule. If the laws oppose this, it was legitimate to peacefully – but still conflictually – break them."
Mads Christensen, the director of Greenpeace Nordic, was scathing of the Danish authorities. "The unnecessary imprisonment of these activists has effectively been punishment without trial. It has piled a further 'climate injustice' on top of world leaders' failure to agree a legally binding treaty to cut greenhouse gas emissions."