Mastro, a partner at the Dechert law firm, is representing a trio of homeowners arguing the Mamdani administration has put the burden on them to demonstrate their local residency and why they shouldn’t be wrapped into the pied-a-terre tax, set to affect New Yorkers with second homes worth at least $5 million, and coops and condos worth at least $1 million.
‘A botched rollout’
Mastro was quick to respond to Mamdani’s comment. “It’s a kind of compliment that I’m on the mayor’s mind, but I’d much rather not have to bring lawsuits on behalf of aggrieved New Yorkers because his administration is breaking the law,” he told the Wall Street Journal.
Earlier this month, Mastro was in court arguing that the Mamdani administration had failed to identify the eligible taxpayers and instead pushed those New Yorkers to hire lawyers in order to secure an exemption from the pied-à-terre tax.
“We’re here about a botched rollout of unparalleled proportions,” Mastro said in a court hearing on the pied-a-terre tax. The New York City Department of Finance has been tasked with determining which taxpayers are subject to the tax and began sending out notices in July to those who were possibly eligible.
Mastro has also been waging a legal fight against Mamdani’s proposal to freeze rent. On June 25, the New York City Rent Guidelines Board voted 7-1 to bar rent increases on about one million rent-stabilized apartments with one- and two-year leases. It quickly drew a legal challenge from landlords who argued Mamdani illegally influenced the board’s decision-making process.
“They left landlords to drown,” Mastro said in court.
Mastro maintains his belief in ‘rule of law’
The veteran lawyer served as deputy mayor to New York City Mayor Eric Adams in his last year in office. He resigned in September 2025 and told Bloomberg he’d “never work for a socialist.” He claims bipartisan credentials by citing he has sued Republican and Democratic administrations alike.
“Who better than a former deputy mayor who litigates to know when local government screws up,” Mastro told City & State. “I’m non-denominational. I’m not a politician. I’m just a lawyer who believes in the rule of law and holding the government accountable when it breaks it.”
Mastro is also involved in other legal battles against the Mamdani administration. He has represented East Village residents attempting to prevent the relocation of a new homeless shelter into their neighborhood and sued to push New York City to adopt an open primary process.
Joseph Zeballos-Roig is a policy and politics journalist based in Washington D.C with a focus on economics. He is experienced in connecting the significance of events in the capital to the lives of everyday Americans whether its taxes, tariffs, interest rates or federal programs.
