The celebrity-driven campaign to kill New York University’s expansion plan is down to one last hope. But if Matthew Broderick & Co. get their way, green spaces across the city will be at risk.

NYU has already cut back the original proposal for its Greenwich Village campus over the course of the city’s years-long review process. It’s now set to add four new buildings — if it can make it through one last hoop, a case that New York state’s top court takes up this week.

It started when a trial judge dismissed all the critics’ objections to the NYU plan — except one: Property at the edge of NYU’s site — owned by the city Department of Transportation but managed by the Parks Department — includes a handful of trees and recreation areas.

The judge bought the claim that this counts as “implied park land” — which would force a whole new review process, this time by state agencies.

The finding flew in the face of more than 150 years of legal understanding of “parkland” — which is why it got overruled on appeal.

But the well-funded anti-NYU camp took the case up to the state Court of Appeals — which, oddly, agreed to hear the appeal.

It’s not just NYU asking for traditional rules to be upheld. So, too, are City Hall, affordable-housing advocates and even pro-parks groups. The “implied parkland” doctrine, you see, threatens . . . parkland.

Under standing rules, the city can turn underused public spaces into temporary parks. But if doing so risks permanent consequences, it won’t dare “lend out” such space in the first place. Bye-bye, future community gardens and green spaces.

The Court of Appeals erred in even taking this case. Let’s hope it doesn’t double down with a perverse anti-park ruling.