THE DEADLINE FOR the final batch of communities to submit plans on how they expect to boost multifamily housing near transit is now just two weeks away, but the controversial MBTA Communities housing law saga will drag into 2026.

Most cities and towns, the state housing office regularly emphasizes, have gotten on board and submitted plans to zone for a district of multifamily housing near MBTA service areas, as called for in the 2021 law. But a group of holdouts is banking on the very court that declared the legislation mandatory – and enforceable – in January to rule that the mandate is illegal without dedicated funding included in the law.

Marshfield was one of a bundle of towns that wanted a Plymouth County Superior Court judge to declare they cannot be forced to rezone and bear the potential burden of more density. Lawmakers are not permitted to hand down “unfunded mandates” that create financial obligations on cities and towns without a way to pay for them.

But Superior Court Judge Mark Gildea dismissed suits brought by Duxbury, Hanson, Holden, Marshfield, Middleton, Wenham, Weston, and Wrentham, plus taxpayers in Hamilton. Gildea said the towns’ anticipated possible costs were “indirect,” nonspecific, and therefore not in need of dedicated funding from the state. Beyond that, he wrote, there are already available grants for infrastructure needs and the process.

Marshfield appealed to the Supreme Judicial Court, which agreed to take the case directly to consider the unfunded mandate question. The town argues that Gildea should not have agreed to dismiss the case, asserting that they did describe all the elements of an unfunded mandate in their complaint.

“In addition to suffering a irreparable loss of awarded grant funds in enumerated grant programs, it is/was foreclosed from all other discretionary grant funds not mentioned in the statute,” the town argues in its brief. Plus, the town says, there were costs associated with evaluating and drafting the zoning bylaws and presenting them to the Town Meeting, and they expect to have additional costs based on the rezoning.

The Healey administration has provided nearly $8 million worth of technical assistance and grants to more than 150 MBTA Communities to support the implementation of this law, the housing office said.

“The MBTA Communities Act is one of many tools that Massachusetts is using to increase the production of reasonably-priced housing and lower costs for everyone,” Executive Office of Housing and Livable Communities Secretary Ed Augustus said in a statement, noting that 6,000 new housing units are already in the pipeline in the communities. “We continue to work with the remaining communities to support them in passing zoning that meets their needs, as well as moving forward on many other initiatives to make housing more affordable,” he said.

Marshfield is using the SJC’s own conclusion earlier this year as the basis for the town’s grievance. Writing for a unanimous court on a suit brought by Attorney General Andrea Campbell against the town of Milton, which was resisting compliance with the new statute, Chief Justice Kimberly Budd stated plainly that the MBTA Communities law is not a suggestion.

Because the law itself says cities and towns “shall” zone for multifamily housing, “it is clear that the Legislature intended to require MBTA communities to comply with the act,” she wrote in a footnote. To enforce it, the court concluded, the attorney general’s office can wield the sweeping powers of her office and penalties for noncompliance are not limited to losing four state funding sources listed in the initial legislation.

The high court spent much of its energy in oral arguments and its ruling on the consequences for recalcitrant municipalities, appearing piqued at some points that the cities or towns might simply decide to take a financial hit to avoid rezoning.

“If we were to adopt the town’s interpretation, the only consequence to an MBTA community for failing to comply with the act would be the loss of certain funding opportunities,” Budd wrote in the Milton ruling. “Thus, those communities, like the town in this case, which choose to forgo the identified funding programs, would be free to ignore the legislative decision to require towns benefiting from MBTA services to permit their fair share of multifamily housing near their local MBTA stations and terminals.”

This, she said, would “thwart the Legislature’s purpose by converting a legislative mandate into a matter of fiscal choice.”

Either enthusiastically or through gritted teeth, 92 percent of all MBTA Communities have passed new zoning so far, according to the state housing office.

Three communities facing a December 31 deadline have not yet adopted new zoning, and 10 municipalities did not meet a July deadline and have yet to adopt MBTA Communities zoning. Marshfield is not among them, having passed compliant zoning in October as a precaution.

The housing office and Marshfield are scheduled to file additional briefs in January, and the court could hear the case as early as February.

“We appreciate the 164 communities, including Marshfield, that have put zoning in place to comply with the law,” Campbell said in a statement, “and given the urgency of addressing the housing shortage, we look forward to the SJC taking up this most recent challenge early next year to clarify, once and for all, that every community must comply with the law.”