Oral arguments over the NECEC power line to Canada proposed by Central Maine Power were heard last week by the Maine Supreme Judicial Court (SJC). Now we wait for the court to rule on some highly consequential issues.

To recap: After Hydro-Quebec, which has surplus hydroelectric power to export, failed to connect with Massachusetts consumers through New Hampshire (“Northern Pass”) in 2017, Bay State utilities had a backup plan, extending an existing transmission corridor north from Lewiston, including 53 miles of new construction.

NextEra, a big generation market player, battled Hydro-Quebec before Massachusetts regulators, then tried to block the Maine project, failing when the SJC rejected its challenge in March 2020. Then, with funding from several fossil fuel generators, it helped organize subsequent referendum drives, though the public face has always been environmental groups.

NextEra has built solar installations in Maine, and would have built more had it gotten the 1,200-megawatt Massachusetts contract, but its portfolio is still weighted to fossil fuels — exactly the kind of power environmentalists also insist we have to replace to counter global warming.

The SJC isn’t interested in such facts, only the law. After ruling the 2020 referendum question off the ballot, it’s now considering the 2021 version, which passed by nearly 60%.

In retrospect, the referendum was more a test of CMP’s customer relations — dismal — than a considered view of the project’s merits, which hardly figured in the debate. Now, we’ll see whether the vote to shut down the project stands up to constitutional tests.

Two appeals are being heard together: a challenge to the project denial, and a Superior Court judge’s ruling that public reserved lands lease for one mile of the northern 53 miles was improperly granted.

This is a substantially different court than existed when Gov. Janet Mills began appointing new justices, a year into her first term. That was apparent from the oral arguments.

The seven-member court could muster just four justices — Chief Justice Valerie Stanfill, who’s served a year; veteran Joseph Jabar, on the court since 2009; Thomas Humphrey, appointed in 2015; and Andrew Horton, one of Mills’s first appointees.

There were three recusals: two more Mills appointees, Catherine Connors and Rick Lawrence; and Andrew Mead, a 2007 appointee and now the senior justice.

Judges generally don’t give reasons for standing down, but Lawrence has been on the court only a few weeks, and Connors was a private litigator, possibly handling cases for one of the parties. Mead’s recusal has no obvious cause.

The short-handed panel was buttressed by active retired Justice Robert Clifford, but most questions came from Stanfill and Jabar. The new chief justice, by all accounts, acquitted herself well.

Though speculation is not without risk — unlike the U.S. Supreme Court’s abortion case, there have been no leaks —  the court seemed skeptical of the Superior Court ruling on public lands, managed by the Bureau of Public Lands (BPL).

The possibility the power line would “substantially alter” other public uses seems slight. Virtually the entire parcel is already managed for timber, harvested most recently in 1986-87 and 2006-07.

Another power line already runs through the 1,241-acre parcel; “pristine” it’s not. The likely outcome is for remand to Superior Court.

The main menu item, the line itself, is harder to handicap. The advisory ruling that blocked the 2020 question raised a serious “separation of powers” issue where it tried to invalidate a decision by the Public Utilities Commission the court had already upheld in the NextEra case.

But judges are loath to wade into relations between legislative and executive branches, or, with the PUC, an independent agency. Veteran court observers said the court seems unlikely to go there.

Instead, the referendum could be overturned on the basis of “vested rights,” subject to both a state law and constitutional provisions.

The state constitution prohibits any “ex post facto law, nor law impairing the obligation of contracts.” In practice, this means the investments made by CMP cannot be simply wiped away through a subsequent law.

NECEC opponents correctly point out that many state laws have retroactive effects, but contractual rights are different. Nor are the justices likely to be swayed by the argument CMP “should have known” voters might oppose it.

If projects that receive all relevant state and federal (and Canadian) permits could be shut down this way, nothing “controversial” could ever be built. Stanfill did point out, however, that some permits were still under appeal.

The SJC is on new ground, so it’s impossible to predict its rulings from oral arguments; these are only educated guesses. We’ll know in a few weeks, perhaps a bit longer, what the five justices conclude.

Douglas Rooks, a Maine editor, commentator and reporter since 1984, is the author of three books. His first, “Statesman: George Mitchell and the Art of the Possible,” is now out in paperback.  He welcomes comment at drooks@tds.net