Depending on the outcome of a new legal challenge, the Pinelands Commission on Tuesday will once again take up the most controversial project ever to come before it - or maybe it won't.

An environmental group is seeking an injunction to halt Tuesday's public comment session on South Jersey Gas' plan to build a natural gas pipeline through protected pineland forest. The 22-mile pipeline is proposed to run from Mauricetown in Cumberland County to serve a gas-fired electrical generation plant in Cape May County.

The Pinelands Preservation Alliance alleges that Tuesday's session is not a proper hearing, but is, instead, part of a new review process that the commission adopted illegally at its December board meeting to expedite the pipeline's approval.

The proposed rules change "was never even posted on their agenda," said Jaclyn Rhoads, PPA's deputy executive director. "And when they came out of executive session they didn't share it. They didn't even have copies."

Nancy Wittenberg, executive director of the Pinelands Commission, on Friday acknowledged that the commission had agreed at its Dec. 9 meeting to adopt temporary rules for reviewing utility projects.

That came, she said, in response to a November directive from the Appellate Division of New Jersey's State Superior Court that the commission's 15-member board should make a "final determination" on the pipeline project. She said the commissioners did not want the project languishing while it debated changes to its regulations.

She could not comment on the legality of the board's Dec. 9 actions because she is not a lawyer, she said.

The board will confer by phone Monday, Wittenberg said, on whether to postpone Tuesday's comment session in light of PPA's complaint.

Rhoads said she expects the Appellate Division will decide quickly on whether to invoke PPA's injunction request if the board votes to hear comments.

Debate over the pipeline has been so passionate that the commission relocated Tuesday's public comment session to St. Ann's Roman Catholic Church in Pemberton Township to handle the anticipated crowd.

The hearing is part of the commission board's regularly scheduled monthly meeting, which will start at 9:30 a.m.

A vote on the project is not scheduled.

At issue is a portion of the route that would run through 10 miles of pinelands forest where utilities are banned by the Pinelands Commission's charter, or Comprehensive Management Plan, unless they directly serve the pinelands community.

The new plant would replace the B.L. England coal-fired plant in Upper Township that has for decades been one of New Jersey's major point sources of particulate pollution.

But environmental groups, four former governors, and many private citizens have been emphatic that commissioners must heed the charter's ban on utilities in legally protected pinelands.

"The proposal would compromise the integrity of the Pinelands Comprehensive "Management Plan and serve to encourage future development contrary to the vision the CMP sets out for growth and conservation in the Pinelands," former Govs. Brendan Byrne, James Florio, Thomas Kean, and Christie Whitman wrote in a joint letter to the commission signed Jan. 12.

Their letter, and the PPA's injunction request, are just the latest twist in a saga that began four years ago, when South Jersey Gas first approached the commission with its plan for a 24-inch pipeline project.

Although the company acknowledged that a portion of the pipeline would run through Pinelands where such utilities are barred, it joined with the state Board of Public Utilities in seeking a special waiver on grounds that the route was far less costly than any alternative.

It also said most of it would run invisibly beneath the shoulder of Route 49 with negligible environmental damage.

Then as now, however, opponents argued that allowing the project would set a precedent for more pipelines and high-tension power lines, leading to a degradation of the whole 1.1 million-acre Pinelands. In January 2014, the commission's board rejected the application on a 7-7 vote, but in May 2015, South Jersey Gas resubmitted its proposal, asking for permission to build along the same route that had been rejected.

This time, Wittenberg cleared a path around the board. She declared in August 2015 that because the B.L. England plant is in federal pinelands - albeit not in a part of the Pinelands that the state commission regulates - the pipeline would meet the charter's requirement that it serve the pinelands community.

As such, she said, the project did not need the review or approval of the board of commissioners.

Although some board members expressed astonishment and annoyance in private, Wittenberg passed the application along to the Board of Public Utilities, which declared in December of that year that it was clear to proceed.

But the Sierra Club, PPA, and Environment New Jersey quickly challenged Wittenberg's and the BPU's actions. On Nov. 7, the Appellate Division ruled that she had overstepped her bounds, and instructed the Pinelands Commission to make a final determination on the South Jersey Gas pipeline project.

The appellate judges also directed the commission to adopt a new review procedure for future applications from private utilities. The commission must also review another controversial pipeline, called the Southern Reliability Link, proposed between Chesterfield Township, in Burlington County, and Manchester Townships, in Ocean County.

But the Preservation Alliance and other opponents of the pipeline say the resolutions the board adopted in December seem calculated to thwart public opposition, and win pipeline approval, and they want the court to stay them.

The commission "failed to adopt and apply proper review procedures to ensure that development projects in the Pinelands comply with the CMP," the alliance asserts in its injunction request.