In a last-minute tweak to the 2018 budget Tuesday, City Council Melissa Mark-Viverito defied Mayor Bill de Blasio's ongoing attempt to exclude certain at-risk immigrants from tax-funded legal representation.

Since de Blasio announced his $85 billion budget this spring, he's sparred with Mark-Viverito and a broad coalition of public defenders and immigration advocates over a new pot of money dedicated to funding lawyers for indigent New Yorkers at risk of deportation. The mayor has sought to restrict the $16 million funding stream, excluding immigrants with any of 170 convictions deemed "violent and serious."

Mark-Viverito, meanwhile, has insisted that doing so would undermine a first-of-its-kind program and limit due process. The New York Immigrant Family Unity Project, established in 2013, provides legal counsel to all immigrants in detention who cannot afford a lawyer, regardless of their criminal history. The program fills a legal loophole, as the US Constitution does not guarantee legal representation in immigration court.

According to public defenders, immigrants with convictions on the list of 170—including burglary and drug possession in the first and second degree as well as rape, murder and arson—have particularly complex options for relief in immigration court, and don't stand a chance without representation. Attorneys also argue that the category of convictions is broad, and includes convictions for minor, non-violent offenses.

A 2011 New York Immigrant Representation study found that 67 percent of immigrants in detention faced judges without legal representation before NYIFUP. Of those defendants, only 3 percent won their cases. Legal representation increases defendants' chances of avoiding deportation tenfold, the group found.

Eleventh-hour language in the FY 2018 budget states that eligibility for immigrant defense funding, including $10 million in City Council funds on top of the mayor's $16 million commitment, "shall be based solely on income."

Mark-Viverito declined to comment on the new language, which landed in the budget days after Mayor de Blasio told reporters that he and the speaker were "acknowledging a difference [of opinion]." She walked swiftly out of City Hall on Tuesday, trailed by a pack of reporters, deferring comment to the City Council's spokeswoman.

"NYIFUP has become a national model that has helped stop hundreds of unjust deportations and keep families together," Council Spokeswoman Robin Levine stated Tuesday. "The Speaker and City Council are fully committed to defending the integrity of this vital program and to upholding due process for all New Yorkers, which is why we have amended the budget to ensure continued, unrestricted access to legal services for all detained immigrants facing deportation."

City Hall, meanwhile, maintains that it has the final word on how the full $26 million will be allocated, through a contracting process that the executive branch is responsible for. The Mayor also has veto power, his office confirmed, though he has never exercised it.

"There is a clear, respectful difference of opinion between us and the Speaker on this issue," said City Hall spokeswoman Freddi Goldstein. "Our position remains unchanged. We expect this to be resolved during the contracting process."

Law professor Peter Markowitz of the Immigration Justice Clinic At Yeshiva University said Wednesday that even if Mayor de Blasio could technically continue to push back on Mark-Viverito's last-minute provision, doing so would not be good for optics.

"To actively try to undermine the City Council's ability to apply its own funds," he said, "that seems like an overreach that would be a somewhat surprising thing."

The New York City Bar Association recently came out in support of the City Council's position, along with former chief judge Jonathan Lippman and former assistant chief immigration judge Sarah Burr.

The Mayor's Office has maintained that New York tax payers should not have to "foot the bill" for defendants with serious convictions, when other programs, like Immigrant Children Advocates' Relief Effort, are also vying for funds.

On Friday, de Blasio described the group with serious convictions as a "very small number of people" and insisted that he and the Council Speaker "agree that the city of New York should help undocumented people who are facing deportation."

NYIFUP picked up 325 clients between December 2016 and May 10th of this year, according to data supplied by City Hall. Of these defendants, 63, or 19 percent, had convictions on the list of 170.