The Massachusetts Supreme Judicial Court has agreed to hear an appeal on NorthPoint, the beleaguered $2 billion Cambridge mega-project, that will determine, in part, if more than 25 percent of the site’s 40 acres were improperly permitted and should be classified as state lands.

The new suit was brought by the same Cambridge residents who successfully challenged NorthPoint’s state environmental exemptions two years ago.

That SJC decision didn’t just derail the then-struggling 5 million-square-foot construction project. It also threw into question the titles on several million square feet of building space in Boston and Cambridge, setting off panic in the state’s development community and requiring a special corrective law from Beacon Hill.

Now, NorthPoint’s neighbors are heading back to court. They’re arguing that the special law the legislature passed in response to their first lawsuit didn’t specifically clear the clouds surrounding NorthPoint. In fact, they say, a full 13 acres of the 40-acre site was improperly permitted and later put on the market.

Now the SJC will rule on whether the state, not Pan Am Railways, holds title to those 13 acres, which cut through the middle of the project site.

"The railroad had a license to fill in" 13 acres of disputed tidal lands, said Steve Kaiser, one of the plaintiffs. "But they had no right to use that land however they wanted, or to sell it. They don’t own it. They don’t have fee title to it. The license, from 1962, says they need a new license for a change of use."

This week’s SJC ruling granted the plaintiffs direct appellate review, bypassing appeals courts and sending the case directly to the state’s highest court. The SJC clerk’s office said that oral arguments would be heard this fall, at the earliest.