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Michael Bloomberg has come under attack for his past comments about women and support for stop-and-frisk policing. But his rivals have yet to raise a lesser-known part of his record that could be as damaging: When last in power, Bloomberg presided over the mistreatment of Democrats who sought to protest Republicans, violating the constitutional rights of hundreds of dissenters.

At the time, Bloomberg was a first-term Republican mayor of New York. The GOP hoped that holding the 2004 Republican National Convention in the city, a site of the 9/11 terrorist attacks, would help reelect George W. Bush. Protests in deep-blue New York were inevitable. Bloomberg had months to prepare.

And he did. Nearly as soon as the convention location was announced, the police department that Bloomberg presided over launched a secret mission to infiltrate protest groups, The New York Times later reported:

For at least a year before the 2004 Republican National Convention, teams of undercover New York City police officers traveled to cities across the country, Canada and Europe to conduct covert observations of people who planned to protest at the convention, according to police records and interviews.

From Albuquerque to Montreal, San Francisco to Miami, undercover New York police officers attended meetings of political groups, posing as sympathizers or fellow activists, the records show.

Some people planned to break the law during protests, but in hundreds of secret reports, the NYPD “chronicled the views and plans of people who had no apparent intention of breaking the law,” including “members of street theater companies, church groups and antiwar organizations, as well as environmentalists and people opposed to the death penalty, globalization and other government policies.”

Spying was just the beginning.

About a month before the convention, district-court Judge Robert W. Sweet ruled that the NYPD had been unconstitutionally restricting access to early demonstrations, and unlawfully confining demonstrators in pens and searching them. The judge’s ruling barred the use of those tactics at the RNC proper.

After the RNC began, Bloomberg failed to safeguard the right of dissenters to peaceably assemble while presiding over dubious arrests. The debacle ended in a class-action civil-rights lawsuit and an $18 million settlement.

A judge who ruled on the legality of the policing tactics gave an account of one mass arrest of peaceful protesters:

The undisputed facts indicate that the police granted permission to the protesters to conduct their march on the sidewalk, only to have that permission abruptly revoked. The undisputed facts, particularly the video, confirm that the marchers on Fulton Street were attempting to comply with police instructions and that the revocation of consent for the march came suddenly and without any realistic opportunity to disperse or correct the problems with the march.

The judge went on to characterize the city’s defense as “one of group liability”: essentially, that the unlawful acts of a few members of a massive group of protesters justified the arrest of everyone. If a few people in a group of hundreds started blocking the sidewalk, the protocol was to throw them all in detention.

In total, 1,806 people were arrested during the convention. Some were legal observers and members of the press. Some were mere bystanders who unwittingly encountered protesters while walking in the city and got swept up in indiscriminate mass arrests. “I was just walking by––I had a receipt from a store that I had bought something from on that street,” Veepa Majamutar told Democracy Now some 12 hours after her arrest. “All of a sudden the street basically just gets cordoned off and we cannot move. So before I was arrested I was just standing still because that's all we could really do. And then they just started putting handcuffs on people. They gave us no warning.”

She went on to describe the conditions at Pier 57, which the NYPD used to cage dissenters during the convention:

So many of us are cold ... Some of us need medical attention … It's been more than 12 hours now. They ridicule us if we start to complain. And the conditions here are atrocious. It's dirty. It’s smelly. It’s filthy. We don’t have a blanket ... We are sitting on the floor. There's dirt on the floor. There’s oil on the floor. It's smelling bad. We are like a hundred people in a very small room … It's almost like rats in a hole ... I mean, all our clothes are dirty, our hands are dirty. We had to eat an apple with our extremely dirty hands because we have no tissue paper, nothing to clean our hands with. We are just basically packed. Nobody can sit down. They don't even give us a plastic bag to sit on. They don't even give anything to lie down on. We just have to lie on the hard floor, basically. And there is not enough space for everybody to lie down because we have to sit so close.

The Guardian later reported that, upon release, some people were taken straight to the hospital for treatment of rashes and asthma “caused by oil-soaked floors and chemical fumes.” Simone Levine, a representative of the National Lawyers Guild, said during a contemporaneous television interview:

The police department has known for over a year that they are going to be having the Republican National Convention here. They have said for over six months that they expect 1,000 arrests a day, [yet] they provided a detention facility which was slick with oil, which is causing people to have chemical burns. It used to be a bus depot. And they have a holding facility in which we have received calls from demonstrators that they have been held in for 20 and 30 hours.

Were the detention-center conditions the result of administrative incompetence or premeditated cruelty? Neither option speaks well of the mayor who was in charge of the crackdown and wants to preside over the entire federal bureaucracy. The truth is hard to determine, partly because the mayor’s office fought to suppress 1,900 pages of internal documents detailing surveillance and planning in advance of the RNC. “So now and forever,” the New York Times columnist David Carr later mused, “the reason that 1,800 people were arrested, many preemptively, during the convention and placed in a pen on the Hudson River—nicknamed Guantanamo on the Hudson by some—will remain very much a mystery.”

The New York Civil Liberties Union published a report in the controversy’s aftermath noting that more than 90 percent of those arrested had had their cases dismissed or conditionally dismissed, or were acquitted as of July 2005––and that “on top of the fact that hundreds of people were held far longer than the 24 hours permitted under state law, the NYPD was accused of intentionally delaying the release of protesters to keep them from participating in demonstrations taking place while the President was in the city.”

Democrats should not want a president who prepares for political gatherings by conducting intrusive surveillance of those who intend to dissent outside; a president who oversees mass arrests of peaceful protesters, houses them in makeshift detention centers with filthy floors and noxious air, and treats some arrests as justified even when the arrestees were trying to follow the law.

How would they react if Donald Trump did any of that?

No lawful protester should be treated like a criminal. Elected officials are bound not only to tolerate protest, but to affirmatively protect and defend the rights to free speech, peaceable assembly, and political dissent. Bloomberg failed that test repeatedly during his tenure. If Democrats nominate him, they will force a choice between two authoritarians in the 2020 election.

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