A 70-year-old registered Democrat and former deputy mayor is now the Mamdani administration's most persistent legal adversary, filing five lawsuits and counting against a City Hall he accuses of breaking the law.
Randy Mastro, a career litigator at Dechert Law Firm who once prosecuted Teamsters racketeers and helped dismantle Mob corruption at the old Fulton Fish Market, has turned his attention to New York's youngest mayor. Since Zohran Mamdani took office in January, Mastro has challenged the administration's marquee policy rollouts in court, and a state judge has already handed him an early victory on the biggest one.
Staten Island Judge Wayne Ozzi, a Democrat on the state Supreme Court, issued a temporary restraining order blocking the city from enforcing its pied-à-terre tax, a surcharge on second homes worth more than $5 million and condominiums worth more than $1 million when the owner does not use the property as a primary residence. The ruling halts collection of the surcharge and freezes all deadlines while the case moves forward, Breitbart reported.
The judge found that City Hall had caused irreparable harm by publishing a supplemental property roll that exposed the names, addresses, and property values of more than 900,000 New York homeowners, without first determining whether any of those properties actually qualified for the surcharge. Roughly 17,000 owners had already received notices, and a hearing is set for August 31.
That last detail matters. Under the law, the city, not the homeowner, bears the burden of making an individualized determination about whether a property is a non-primary residence before sending a tax notice. Mastro contends the administration skipped that step entirely and blasted notices to people who plainly live in the city full time.
Mastro told the New York Post the rollout was indefensible:
"That's not how the tax system is supposed to work. I even got one of those notices and I have been living here as a primary residence for years."
He was blunter after the restraining order came down. Fox News quoted Mastro saying the city "screwed this up... got it wrong" and demanding officials "stop the train and make them do it over."
The Mamdani administration has not conceded the point. Spokesman Matt Rauschenbach said the city disagrees with the ruling and remains "confident in both the pied-à-terre surcharge and the City's ability to implement it fairly and effectively." The mayor's office vowed to appeal immediately.
Mamdani himself framed the tax as a matter of fairness. "We will diligently implement this law and ensure that we collect what working New Yorkers, and this city, deserve," the Washington Examiner reported him saying. Advocates have projected the surcharge could raise $500 million a year. But the projected revenue depends on the city getting the mechanics right, and so far, a judge has concluded it did not.
The pied-à-terre tax is not the only front. Mastro is also challenging the administration's freeze on rents for stabilized apartments, arguing that Mamdani violated the City Charter, New York City's governing constitution, by packing the Rent Guidelines Board with political allies and running sham public hearings.
Under the charter, the Rent Guidelines Board is supposed to function as an independent, fact-finding body that weighs evidence from both landlords and tenants before deciding whether to adjust rents. Mastro says that process was gutted. He told the Post:
"It's illegal because [the Rent Guidelines Board] is an independent, fact-finding body and is supposed to make this determination, and Mamdani stacked the board with his people."
He added that the public hearings failed to give landlords a real platform. "The public never had a true hearing of the costs faced by landlords, whether they can even afford the rent freeze or whether it's better just to keep these apartments vacant," Mastro said.
That last line points to a practical consequence the administration has not addressed publicly. If landlords cannot cover maintenance costs under a rent freeze, the economic incentive shifts toward keeping units off the market altogether, shrinking the housing supply the freeze is supposedly meant to protect. Mamdani's administration has faced growing criticism from even Democratic establishment figures over his tax and policy agenda.
New York City Councilwoman Inna Vernikov offered a sharper assessment of the broader pattern. "This is Marxism in practice: consistently promising to better the lives of the middle class by punishing the wealthy," she said.
Beyond taxes and rent, Mastro has taken on a third line of attack: representing an investigative reporter pro bono in a case involving alleged antisemitism inside City Hall. The reporter submitted information requests seeking records related to the allegations, and Mastro says those requests were stymied by the administration.
Neither the reporter's name nor the specific records at issue have been disclosed publicly. But the case fits a pattern of an administration that, by Mastro's account, resists transparency and accountability across multiple fronts. Mamdani has faced separate backlash on issues tied to his stance on Israel, including demands from 9/11 families that he stay away from the 25th anniversary ceremony at Ground Zero.
Mastro summed up his posture in a single sentence: "I've got five lawsuits [and counting]. If [Mamdani] is still breaking the law there may be more."
Mastro's willingness to pick fights with powerful people is not new. During the Giuliani administration, he served as deputy mayor and led the cleanup of Mob corruption at the old Fulton Fish Market, work that made him a target of La Cosa Nostra. He later prosecuted Teamsters for racketeering, represented former New Jersey Governor Chris Christie during the Bridgegate scandal, and won a recent case blocking a subsidized housing project in lower Manhattan.
He returned to City Hall under Eric Adams as first deputy mayor. When Mamdani, a 34-year-old former assemblyman, won the mayoralty, Mastro publicly declared he would not "work for a socialist." He went back to private practice at Dechert and started filing suits.
An unnamed former colleague captured the dynamic with a warning aimed at the administration. The colleague acknowledged Mastro could be difficult, calling him "a real a**hole", but added: "Make no mistake, this guy is an excellent litigator and he doesn't care about people's feelings no matter how powerful they are."
The colleague's advice to City Hall was blunt: "Your incompetence will be exposed going up against Randy Mastro."
Mamdani, for his part, has tried to wave off the legal barrage with humor. "There are few things more certain in New York City than death, taxes and Randy Mastro filing a lawsuit against this administration," the mayor quipped. That line landed better before a judge blocked his signature tax policy.
The mayor's troubles extend well beyond the courtroom. A Gold Star family recently blocked him from speaking at a fallen soldier's funeral in Queens, and the city's teachers' union president has broken with him over falling reading scores and stalled paraprofessional pay. When a mayor is losing courtrooms, classrooms, and funerals at the same time, the problem is not one litigator, it is the record he keeps challenging.
Mastro is not leading a political campaign. He is doing what litigators do: reading the statute, finding the violation, and making the city answer for it. If the Mamdani administration keeps cutting corners, the docket will keep growing.
