A judge ruled on Thursday that the city wrongly issued a building permit for a controversial Upper West Side supertall and ordered that the project undergo another review.

The decision, handed down in state Supreme Court, gave a rare victory for community groups and elected officials who had fiercely opposed the 670-foot tall residential tower at 200 Amsterdam. The Committee for Environmentally Sound Development and the Municipal Art Society jointly filed a legal challenge in October 2018, arguing that air rights for the project relied on an illegal assemblage of separate parcels on the block connected by thin strips of land.

While community members have been celebrating the verdict, their victory may be short-lived, as the planned 51-story building is already well under construction. At a glance, developers SJP Properties and Mitsui Fudosan appear to be nearing the halfway point.

The court notably stopped short of ordering the developer to stop construction. Instead, the plans must go back to the Board of Standards and Appeals (BSA), which last July affirmed the Department of Building’s decision to issue a building permit despite a concession by the agency that the irregularly shaped zoning lot should never have been approved.

“We’re in unchartered waters,” said George Janes, a planning consultant who filed the zoning challenge on behalf of The Committee for Environmentally Sound Development, a group that seeks to curb overdevelopment on the Upper West Side.

He added: “By not stopping construction, the court has made this more complicated.”

Developers have in the past built through legal challenges, according to Janes. They have reason to be bold: the majority of cases uphold the city’s decision to issue the permit. And in the instances when they do lose, they can apply for a variance by arguing that it would pose an undue hardship to deconstruct the project.

However, at the time of the legal challenge, the developers of 200 Amsterdam told the court they would not use the progress of their construction to argue that the project was entitled to continue. In other words, they would proceed at their own risk.

It is unclear how that statement, which was noted in the judge's decision, will impact their ability to argue hardship before the BSA.

In a statement to Crain’s, SJP said:

"The development team for 200 Amsterdam has followed the law completely and continues to make construction progress. 200 Amsterdam’s zoning permits were exhaustively reviewed by both the Department of Buildings and the BSA, the two city agencies with the primary responsibility for interpreting NYC’s zoning codes. Following thorough analysis and public testimony, both agencies determined that the building fully conforms with the city’s zoning laws.”

The unexpected court ruling is the latest in a series of blows to supertall developers. In January, after community backlash, the city proposed closing a loophole that allows developers to use mechanical spaces, also known as “voids,” to add extra height to buildings. The zoning amendment, which must ultimately be approved by the City Council, is currently before the City Planning Commission. The state also appears to be on the cusp of approving a pied-à-terre tax, which would assess a fee on part-time luxury homeowners in New York City, many of whom buy units in supertalls.

"Maybe the whole atmosphere has changed," mused Olive Freud, president of the Committee for Environmentally Sound Development. "Developers are taking away our sky and leaving us in shadows. Enough people are angry."