Towns and cities do not have the ability to opt themselves out of the state’s MBTA zoning law, according to the state’s highest court.

In what the Attorney General describes as a “resounding victory for the Commonwealth,” the Supreme Judicial Court ruled Wednesday that MBTA Communities Act is both constitutional and enforceable, ending efforts in the town of Milton and elsewhere to exempt themselves from zoning rules indicated by the law.

“The state’s highest court has made clear that communities subject to the law must allow for additional, responsible development — and that the law is mandatory, not voluntary,” Attorney General Andrea Joy Campbell said in a statement.

The court’s decision means that cities and towns can be sued by the state for failing to comply with the zoning law, which aims to see more housing developed in cities and towns served by the MBTA. The law requires cities and towns to zone for multifamily homes in at least one local district.

“We declare that the act creates an affirmative duty for each MBTA community to have a zoning bylaw that allows for at least one district of reasonable size where multifamily housing is permitted,” the SJC wrote, noting such a ruling is in keeping with “art. 30 of the Massachusetts Declaration of Rights.”

The court did rule that the way the state attempted to implement the law was not in keeping with established rules for doing so, and that the Executive Office of Housing and Livable Communities must file notices and small business impact statements in accordance with the states Administrative Procedure Act.

“Because HLC failed to comply with the APA, HLC’s guidelines are legally ineffective and must be repromulgated in accordance with [state law], before they may be enforced,” the court wrote.

This is a developing story.