The attorney general’s office initially agreed with the interpretation but after inquiries from CommonWealth this week, officials said they reconsidered the decision and issued the new order.

“Upon further review, we now determine that this approval was given in error,” Hurley wrote to Bellingham officials Friday, citing a previous 2013 decision by the office to disallow a similar ban in Wakefield. “As explained in our decision in the Wakefield case… such a ban would frustrate the purpose of [the medical marijuana law] to allow qualifying patients who have been diagnosed with debilitating medical conditions reasonable access to medical marijuana treatment centers. [The law’s] legislative purpose could not be served if a municipality could prohibit treatment centers within its borders, for if one municipality could do so, presumably all could do so.”

Hurley sent a similar missive on Friday to officials in Northborough, which had passed a measure barring “medical marijuana treatment centers,” another name for dispensaries. State law requires communities to wait 90 days before a bylaw is enacted and, with the attorney general’s initial approval, that time frame had passed. But Hurley warned town officials they “should strongly consider not enforcing the ban.” It is the first time under Healey the office has reversed a prior decision to a municipality.