It was an expensive decision by the Copenhagen Police to pre-emptively arrest over 900 climate demonstrators during the 2009 UN climate conference almost exactly three years ago.

According to Politiken newspaper, Copenhagen Police have so far paid 4,203,000 kroner in compensation to 516 people who were caught in the mass arrest on 14 December 2009.

This January the Eastern High Court upheld a ruling by the Copenhagen City Court that found the police had exceeded their powers by making the mass arrest.

Those arrested were in a group at the back of a larger demonstration that police feared had become infiltrated by violent anarchists, known as the ‘Black Bloc’.

In an attempt to capture them, the police executed a pincer movement and arrested the 1,000 strong section of the demonstration as it neared the city.

The demonstrators, who included monks, nuns and then elderly, were forced to sit in rows on the road with their arms bound behind their backs in sub-zero temperatures for several hours.

The ruling at the Eastern High Court reduced the maximum amount each protestor could claim from 9,000 kroner to 3,300 kroner, while also increasing the number of people that qualified for compensation.

The police may yet have to pay out even more money, however.

“We are waiting for the bank details of a few foreigners, but it’s not really that many,” police spokesperson Klaus Pedersen said.