HALLOWELL — Boston-based First Wind is pushing Maine utilities regulators to approve for a second time its multimillion-dollar partnership with Nova Scotia-based power company Emera, in a case that was sent back to the Maine Public Utilities Commission by a court order.

Opponents of the joint venture have argued it violates the state’s electricity deregulation law, which passed in 2000, and stands to give wind farms partly owned by Emera’s subsidiary an unfair competitive advantage over other power generators in accessing the company’s transmission and distribution lines.

In petitioning the PUC for a new approval after the state’s high court struck down the commission’s first authorization of the partnership, First Wind and Emera say the revised dealadvances the state’s renewable energy development goals and that specific regulations governing the deal provide enough protection from opponents’ concerns of favoritism. They also argued that there is still room within the Maine Supreme Judicial Court opinion for the $360 million partnership to move ahead.

Those arguments have reversed earlier opposition by the PUC’s public advocate, whose job is to represent ratepayers in regulatory cases.

The Industrial Energy Consumer Group, which opposes the joint venture along with Houlton Water Co., criticized that reversal in a legal brief filed Friday with the PUC, arguing the deal would create an incentive for favoritism between Emera Maine and the sister company that would own a stake in wind power resources.

As that case progresses before the PUC, First Wind expressed confidence to the Department of Environmental Protection that the $360 million investment from Emera will move ahead to support part of its projects in Oakfield, Hancock and Bingham.

Construction on the Oakfield project is underway with power generation expected to start in 2015. It is planned to have 50 turbines and a capacity of 148 megawatts. The Hancock wind farm would have a capacity of 51 megawatts, with 17 turbines.

Bingham would be the company’s largest, rated at 186 megawatts, and is still under Maine Department of Environmental Protection review.

In documents filed with the DEP earlier this month, an attorney for First Wind said the court ruling “does not have any immediate impact on First Wind’s ability to finance its projects in the Northeast” because it set out a new legal standard for the joint venture to meet but did not invalidate it outright.

“We believe that the joint venture satisfies the legal standard articulated by the Law Court and should be affirmed on that basis,” wrote attorney Juliet Browne, on behalf of First Wind.

The court decision directs the PUC to determine when a financial relationship is sufficient to give a transportation and distribution company an incentive to favor one power generator over another.

Without the Emera deal, First Wind told the DEP it could finance its projects in other ways. The company announced May 1 that it arranged a $369 million financing deal, its first since the Law Court’s ruling, for its 148-megawatt Oakfield project.

The deal would involve Emera taking up to a 49 percent stake in the joint venture JV Holdco through a subsidiary Northeast Wind, which would own a stake of certain First Wind projects. Emera is also the parent company of Emera Maine, which is the electricity transmission and distribution utility for approximately 154,000 electricity customers in northern and eastern Maine.

The case is also attracting attention from the state’s other investor-owned utility, Central Maine Power, which supported Emera and First Wind’s argument — while stating neutrality in the case — that federal and state regulations effectively prevent favoritism between transmission and distribution utilities and power generators.

Hearings in that case will continue in the coming months as regulators also consider a recommendation by the public advocate to clarify rules around what kind of financial relationships will be allowed between transmission and distribution companies and power generators.