In my experiences with NYPD blockades as a passerby they typically forcefully imply rather than directly state you're not allowed through, and if you insist I've always seen them sheepishly give up.
The whole point with Kettling, which kinda makes it punitive, is that they are 100% clear that you are not leaving the enclosed pen they have created.
Sometimes the kettling can go on for 6+ hrs and even with protestors demanding toilet breaks, water or medical issues from standing up for so long, the police have refused them to leave.
Sometimes the kettling can go on for 6+ hrs and even with protestors demanding toilet breaks, water or medical issues from standing up for so long, the police have refused them to leave.