Six justices of the Massachusetts Supreme Judicial Court will hear arguments on Mon., Oct. 7, on Attorney General Andrea Campbell’s push to force Milton to comply with a 2021 zoning law. It’s a case that the high court took on because of the new and important public policy issues it deals with.

The court set the specific date for arguments earlier this month, according to the case docket, and the paperwork has been coming in thick from dozens of other municipalities that will be affected by the court’s ruling on their legal obligations and the state’s enforcement powers under the so-called MBTA Communities Act. Those communities are trying to shape the justices’ thinking on the issue.

“This is a case about the separation of powers and the rule of law — about who sets the rules that govern the Commonwealth and how they do so,” the town of Milton wrote in a brief it filed last month.

Campbell filed the lawsuit against Milton and its building commissioner, Joe Atchue, in February, alleging violations of the 2021 law that requires cities and towns near T service to adopt zoning that allows multifamily housing by right in certain areas. She argues that the law does not allow for communities to opt out of new zoning requirements and is seeking court-ordered compliance. Milton officials contend that the only punishment for not complying is ineligibility for certain state grants.

“As the Town suggests, this case is about who holds government power,” Campbell’s office wrote in its reply brief filed last week. “The Legislature, exercising authority that it undisputedly possesses under the state Constitution, has enacted an undisputedly mandatory provision that applies to over 170 municipalities. Milton alone not only has refused to comply with that mandate, but it also insists that the Commonwealth is powerless to make it comply. But Milton cannot wall itself off from the Legislature’s attempt to begin to remediate a housing crisis that affects the entire Commonwealth.”

Justice Serge Georges picked the case for full SJC consideration when he determined in March “that this case raises novel questions of law which are of public importance, and which are time sensitive and likely to recur, i.e., the scope of a municipality’s legal obligations under [the MBTA Communities Act], and under the related Guidelines, and whether the Attorney General has authority and standing to enforce compliance with the same.”

The court’s website shows that Justice Bessie Dewar, the former state solicitor, will not participate when the case is called on Oct. 7 at 9 a.m.

“We’re looking forward to that because we think it would be extremely helpful. We obviously wanted it sooner, but the court decided to delay it,” Campbell said of the arguments Tuesday on GBH Radio. “And we think it will be helpful, because we think they will say — and we’re hoping that, and pushing that through all of our filings — that not only is the MBTA Communities law mandatory, but that our office, and my office, has the authority to enforce it, and because it’s mandatory and we have the authority to enforce it, we also have an obligation and responsibility to work with a municipality that’s in violation of that law to get them to come into compliance.”

There are 177 communities that either have or will have to rezone to encourage multi-family housing because they either host or are adjacent to MBTA service. The mandate, which lawmakers wove into an economic development package at the last minute and without real public debate, is meant to encourage needed housing production but several towns have been considering referendums similar to Milton’s to ignore the law.

Campbell said a week ago Tuesday on GBH Radio that “right now, 175 are taking steps to come into compliance” and added, “So kudos to all those municipalities that will never make a list in the news.” Her 175-town figure represents all affected municipalities minus Milton, which did not comply by its deadline, and Holden, the Worcester suburb that the state considers not in compliance because it has not submitted an action plan and has said it will not comply with the law by its end-of-2024 deadline.

Milton Town Meeting initially approved a zoning reform plan that would have complied with the law. But opponents of the changes worried about excess development pursued a referendum, and a majority of Milton voters chose to spike the zoning plan.

Zoning has long been the domain of municipalities, contributing to lagging housing production in some places, but Campbell wrote in her lawsuit over Milton’s noncompliance that “the Legislature has retained ‘supreme power in zoning matters,’ as long as it acts in accordance with the Home Rule Amendment,” quoting from a 1973 court ruling.

In its August filing, the town of Milton acknowledged that the MBTA Communities Act “is not a toothless mandate: the MCA provides that a non-complaint municipality will lose funding under four state programs.” It argues that the Legislature specifically limited the punishment for non-compliance to loss of state funding.

“The Legislature might have selected an even more forceful enforcement mechanism, such as an action by the Attorney General to require compliance, but it did not,” the town wrote.

It added, “This is a separation of powers issue. In enacting a new statute, the Legislature is entitled to decide that the statutory goal is best advanced through financial penalties and not injunctive relief. Allowing the AG to always pursue injunctive relief, even if the Legislature specified only some lesser remedy, will make it impossible for the Legislature to balance competing policies and interests when establishing new statutory regimes.”

On the argument related to the powers of the attorney general to enforce laws that provide for other specific remedies, Campbell has gotten some back-up from three of her predecessors.

Three men who held the attorney general’s job for a consecutive 24 years – Francis Bellotti (1975 to 1987), James Shannon (1987 to 1991) and Scott Harshbarger (1991 to 1999) – filed their own brief  with the SJC, supporting Campbell’s position and her office’s power to compel Milton into compliance.