Secretary of Commonwealth Bill Galvin is girding up for some shadow boxing. 

When Governor Charlie Baker put his pen on Friday to a bill exempting a proposed skyscraper from state laws regulating the shadow it can cast on Boston Common, it seemed to many that the controversial Millennium Tower project was a done deal.

Not so, Secretary of Commonwealth Bill Galvin told WGBH News on Monday.

In fact, Galvin — by no means the only critic of this special exemption for a particular project, but likely now the most influential — appears ready for a protracted fight over a project that has already been a source of controversy for the better part of a year.

“All this legislation did was remove a layer of protection that was there, which is unfortunate,” Galvin said in an interview. But, he said: “It doesn’t necessarily mean the building is going to be built. There’s still a process to go through, and we’re certainly going to be part of that process.”

By “we” Galvin meant the State Historical Commission, of which Galvin, in his capacity as secretary of state, is chair.

And the process in question is a state environmental impact review, which will include reviewing the impact of the proposed development not just on the Common but on historical buildings in the area.

Galvin was highly critical of the process thus far, noting that the City of Boston never conducted an independent review of the building and its impact; that the developers had revealed the expected shadow only after having skirted city review; and that the developers acknowledged to state officials, after Boston City Council had passed the home rule petition for exemption, that they still weren’t sure how tall the building would be.

But he expects a much more thorough state impact review, he said.

“Obviously I hope it’s done appropriately, and that it’s not short-circuited, as the review the city might have done was,” Galvin said. “And we’ll certainly be a part of that.”   

The tower, which would be built on the city-owned parcel known as Winthrop Square, would cast a shadow on Boston Commo. That meant that the project needed an exemption from laws meant to protect open spaces and historic buildings from being overshadowed by tall buildings.

With Baker’s signature, developer Millennium Partners got that exemption, after having run a political gauntlet through Boston City Council, public outcry, frowning editorials and an uncertain outcome in the state legislature.

That outcome was all the more uncertain thanks to the intervention of Galvin, who appeared before state lawmakers asking them in no uncertain terms to shut the process down, after learning that the developers were still tweaking their plans and that they couldn’t say themselves exactly how big this shadow would be.

And then there was the bargaining: The bill sat for weeks, as stakeholders like the Friends of the Public Garden negotiated with Millennium Partners over whether and how much the developers would pony up in economic (if not solar) mitigation. The shadow of Boston Mayor Marty Walsh – a firm proponent of the development – loomed over the whole affair.

Last week, Friends of the Public Garden announced that Millennium Partners had agreed to contribute $125,000 annually for forty years, in addition to a lump sum payment of about $28 million.

In a written statement, Friends Board Chairperson Leslie Adams acknowledged that the group had “lost the battle to prevent this exemption from state laws.” But, Adams said the funds Millennium has committed would help maintain the Common in the future and that this would be a “one-time” — the words were printed in bold — exception to the shadow laws.

Secretary Galvin was milder in his assessment of such side deals, telling WGBH News that he didn’t blame groups like the Friends of the Public Garden for getting the best deal they could once the city council had approved the home rule petition for exemption.

“I personally think it was unwise,” he said, calling Millennium’s offer “paltry.”

But, he said, “We have to move on now. They [the legislature] have made their decision.

“There is a process," Galvin added. "We’re going to go through the process, and wherever it leads, we’ll see.”