Boston's effort to build a new bridge to Long Island got a lift Monday with a favorable high court ruling.

The Supreme Judicial Court ruled that a state Department of Environmental Protection order supersedes the Quincy Conservation Commission's application denial related to the bridge construction because the commission "did not rest its determination on more stringent local provisions."

"The commission does not explain in its brief, and did not explain in its decisions denying Boston's application, how its own analysis differs from the analysis that the DEP was authorized to perform," the court ruled.

In 2014, Boston closed the bridge connecting Quincy to Long Island, which is under Boston's jurisdiction, for safety reasons. The bridge was removed in 2015, but its piers remain. In 2018, Boston initiated a bridge rebuild effort, which would rely on the existing piers, so the city could restore access to rehabilitation facilities on the island, including opioid addiction treatment services. Before the bridge closed, Long Island housed a multi-bed homeless shelter, drug treatment programs and transitional housing programs.

Because the project would have an impact on wetlands in Quincy, Boston petitioned the Quincy commission for permission to build the bridge. After the commission denied Boston's application, Boston applied to MassDEP for a superseding order of conditions and DEP allowed the project to proceed.

In Monday's ruling, Justice David Lowy cited the 2007 case Oyster Creek Preservation Inc. v. Conservation Commission of Harwich, writing that "a conservation commission's decision regarding wetlands may stand, despite a superseding order by the DEP, if the conservation commission relied on provisions in a local ordinance that are more stringent than the provisions in the act."

"The commission claims it relied on the local ordinance's reference to 'cumulatively adverse effect[s] upon wetland values,' and that this language is more stringent than the language in the act," Monday's ruling said. "However, we conclude that the DEP order supersedes that of the commission because the commission did not rest its determination on more stringent local provisions."

In denying Boston's application, the Quincy Conservation Commission concluded that Boston had not provided sufficient information about how Boston would mitigate the environmental impacts of repairing and replacing the piers, and repairing a road that would provide access to the bridge.

The court said the State Wetlands Protection Act addresses the commission's concerns around how work on the piers would affect fisheries, wildlife habitat, pollution, land under the ocean, and land containing shellfish.

In May, the Boston Herald reported that U.S. Attorney for Massachusetts Rachael Rollins informed Quincy Mayor Thomas Koch in a May 12 letter that her office is "initiating an investigation" into Quincy based on the Americans With Disabilities Act, which includes language forbidding discrimination against people with substance-abuse issues. The Herald reported that Rollins' civil rights unit was seeking information about Quincy's opposition to the project.