As New York police officers disperse and fence in Occupy Wall Street protesters -- a situation that has led to one highly-publicized pepper spraying incident -- questions about First Amendment violations have been raised by the supporters of the demonstrators.

NYPD Commissioner Ray Kelly on Wednesday said Internal Affairs Bureau will look into an video-recorded incident in which a high-ranking officer used pepper spray on four Occupy Wall Street protesters behind orange netting during a march from the Financial District to Union Square in Manhattan, The New York Times reported.

Kelly said that a group was engaged in tumultuous conduct and was intent on blocking traffic, according to the Times. NYPD spokesman Paul Brown on Tuesday defended the officer and told The New York Times that if the demonstrators had a permit, accommodations would have been made to divert traffic to let the march proceed.

But the notion of protesters seeking a permit is misleading, according to one veteran of marches, protests, rallies and demonstrations: New York City civil rights attorney Norman Siegel.

Of all the times I represented groups that marched through the streets of New York, you don't actually get a permit. There's no piece of paper, Siegel said before heading to Midtown Manhattan to rally organized by a Guinea human rights group.

Siegel was a former director for the New York Civil Liberties Union and represented bicyclists from the Critical Mass group who were arrested during the massive protests near the 2004 Republican National Convention held in Madison Square Garden.

He said that in his experience, organizations often communicate with officers about a holding a march on city streets. The NYPD's decision to divert traffic for a street protest is based on logistics and is often made on the spot, Siegel contended.

There are instances where police will allow groups who refuse to communicate with police, like Occupy Wall Street, to proceed, he said.

I've seen the police in those situations allow people to march through the street, Siegel said of. Very often, my sense is it's selective and that's the arbitrariness. In a sense, they make a decision based on who the group is and who they are.

An NYPD spokesperson did not respond to requests for comment on police officers' interactions with demonstrators or on the issue of permitting demonstrations on city streets.

Siegel said he worries about such a seemingly informal process for holding demonstrations with police accommodation.

That's something that always troubled me, Siegel said, as both a policy matter and a constitutionality matter.

Siegel said he offered advice to a few demonstrators who contacted him, including one who was worried about getting kicked out of Zuccotti Park, the base camp for protesters.

Supporters of Occupy Wall Street have taken to Twitter to voice their concern about rights to assemble peacefully being violated.

#OccupyWallStreet shows first amendment is a lie? @ckstopford wrote on Twitter. Yes, we all #Occupy under our basic first amendment rights. We exercise our right to peacefully assemble, @OccupyDenver wrote in a post.