London's cyclists have won a legal contest against the police who wanted to make a monthly bike event unlawful.
The event has been running since April 1994
The long-running Critical Mass event involves cyclists taking to the streets to celebrate safe cycling.
The Metropolitan Police claims it is illegal as it has an organiser who does not give prior warning of the route.
But the High Court said it was not a notifiable procession under the Public Order Act and police did not require advance notice of the timing and route.
The London ride is part of a worldwide phenomenon and has taken place on the last Friday of the month, every month, for the past 12 years, with riders gathering on the South Bank from 6pm.
But last September, before the start of that month's ride, cycle police, who always accompany the cyclists, distributed a letter to participants stating the Critical Mass demonstrations were not lawful.
In a letter described by cyclists as "heavy-handed", the police said "organisers of public processions" were required by law to give at least six days' notice of the date, time and proposed route, plus their name and address.
At the time, the Metropolitan Police said it was not an attempt to prevent the rides from going ahead and that they were committed to "facilitating lawful protests and demonstrations".
One of the regular Critical Mass riders, Des Kay, asked Lord Justice Sedley and Mr Justice Gray to rule that the police were misinterpreting the law and their powers.
Mr Kay said he was "delighted" with the judgment, adding: "Critical Mass is an important part of cycling in London.
"Cyclists in the capital, whether taking part in Critical Mass or not, need all the public protection they can get."
The next Critical Mass cycle ride will take place this Friday.