From NYC Bike Blog

From Vlad at the Glass Bead Collective:
The next NYC critical mass is this Friday 5/29 at 7pm starting at union square north. Come out and enjoy what is now becoming a much safer ride.
We are releasing a new video that takes you inside the New York Critical Mass bike ride from this past March 2009. This immersive short was shot with a 180 degree lens and does a good job communicating what the experience is like.
video posted here, of police harassing the March ride. (this video was posted up earlier on bikeblognyc)
Critical Mass is a leaderless bike ride that takes place in 100s of cities worldwide on the last Friday of every month. The New York Police Department has had a very confrontational relationship with the NYC ride since 2004. From 2004 – 2007, hundreds of police officers were dispatched each month to stop the ride and arrest the participants, deploying helicopters, blimps and undercover officers with video cameras to monitor the ride and engage in the violent take down of the cyclists, initiating a civil rights battle. After much embarrassing media attention and several losses in court, the NYPD were forced to retreat from these tactics. The arrests have stopped, but the police continue to harass riders by giving out tickets to cyclists who do not have lights or bells on their bikes. Anyone receiving this ticket can get it annulled by presenting lights and/or bells and their ticket to a precinct the following day.
Hence - please come to the ride but make sure you have a bell and lights on the front and back of your bike - this will significantly reduce a chance that you will be harassed by the police.
This selective targeting is currently being challenged in federal court in the Five Borough Bike Club vs NYC . See 5bbc.org/parade
This event is no longer just a bike issue, but a civil liberties issue. The harassment of this ride is a direct result of New York City’s police leadership trying to impose a permitting system where spontaneous gathering of citizens would be subject to a permission’s process. In effect they are trying to take away our constitutional right to assembly and association.
We ask all of you to please forward this message around, as well as the links to the video. Put it on your blogs. This is a fun, family friendly activity that protects some of our most fundamental liberties.