A State Supreme Court ruling has upheld the claims of a Long Island developer that it’s a partner in a portion of the redevelopment of the Nassau Coliseum property.

The decision Monday by Justice Vito DeStefano in Mineola denied the motion by Nassau Events Center to dismiss a lawsuit from Syosset-based Blumenfeld Development Group, which claims it remains a 50 percent partner in the retail/entertainment development slated for some of the 77 acres surrounding the planned rebuilt arena.

If Blumenfeld’s lawsuit is eventually successful, it could affect a potential future sale of the arena’s surrounding development to other investors, such as Mikhail Prokhorov’s Onexim Sports and Entertainment, and press a reset button on a major portion of the redevelopment plans. Onexim bought into 85 percent of the Coliseum project in a deal that was announced in October 2015, but it’s unclear whether that sale was only for the arena or also included the ancillary retail/entertainment portion of the project.

The battle between NEC and BDG resulted in dueling lawsuits filed in March 2015. Blumenfeld was ousted from the project by NEC founder Forest City Ratner which claims the two companies’ partnership was never finalized. BDG sued Forest City Ratner for “illegal dismemberment” of their partnership, which they say began in July 2013, with Forest City assuming responsibility for building a new arena and Blumenfeld becoming equal partners in the accompanying retail/entertainment space and future development of the site.

While attorneys for NEC and Forest City Ratner claimed there was never a formal signed joint venture partnership agreement with Blumenfeld, DeStefano ruled that “the complaint pleads the existence of an oral joint venture between the parties” and that there was nothing in the memo of understanding between the two that “addresses the potential termination of BDG’s prior status in the project, much less anything which expressly acknowledges that BDG’s involvement in the project as a publicly touted, high-profile participant would come to a complete halt.”

The court also denied dismissal of the tortious interference and breach of contract claims against Bruce Ratner and the other Forest City defendants noting that the motion was “based on the theory that there was no oral joint venture agreement or that the MOU superseded any alleged oral agreement-theories which the court has already rejected…”

Blumenfeld’s attorney Ronald J. Rosenberg, of Garden City-based Rosenberg Calica & Birney, said the ruling was significant.

“We are very pleased the court sustained BDG’s complaint on the merits and agreed with its legal contentions,” Rosenberg said via email. “We look forward to pressing forward with the litigation to, among other things, fully restore BDG’s rightful place as a partner in the Nassau Coliseum redevelopment project. This is a significant victory not only for BDG, but for all of the taxpayers of Nassau County who have been wondering and waiting for the redevelopment of this property to occur.”

An emailed statement from a Forest City Ratner spokesman said the decision “does not in any way prevent us from moving forward with the development of Nassau Coliseum or the surrounding retail. In fact, we are continuing to make great progress with renovation of the Coliseum, and are looking forward to providing Long Islanders with the project they deserve.”

After working on the Coliseum project for a year, BDG had begun negotiations with several prospective tenants for about 300,000 square feet of restaurants, retail and entertainment businesses that included a 100,000-square-foot Bass Pro Shops mega-store, a Dave & Buster’s, Modell’s, an indoor trampoline park, a multi-screen movie theater and some eateries.

But NEC has planned a smaller, less ambitious retail/entertainment component of about 180,000 square feet that would have a bowling alley, a movie theater and a restaurant to complement its $260 million, 13,000-seat revamped arena.

The next court conference in the case is scheduled for March 22.

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