The cycle ride has been taking place in London for 11 years
The Law Lords are to decide if a group has to give advance notice to police before cycling through London.
In 2006, the Court of Appeal overturned a High Court ruling and said organisers of the Critical Mass ride must notify police giving a date, time and route.
Every month the cyclists gather on the South Bank and ride through the city to celebrate safe cycling.
The Law Lords will have to decide if the event is governed by section 11 of the Public Order Act 1986.
It requires organisers to notify the police in writing of their intention to hold a public procession, and to provide details of the date, route and their own names and addresses.
The cyclists claims although the event is a regular occurrence, no one organises it and the route is never the same.
They have also said that it comes within an exception to the notice provisions because its event is "commonly or customarily held".
That exemption exists because the details of something that is commonly held will already be known to the police, and so notice is not required.
Inspector Nick Rowe, of the City of Westminster Police, said police believed riders were going out "with common cause to demonstrate and as such they should give us notice of where they're going to go".
He said: "There are many different ways in which an event can be seen as being organised and there are certainly people there who have a pretty good idea at the start of the evening which way they're going to go."