The tug of war over the Trans Mountain pipeline expansion is again headed to the courts, as the Federal Court of Appeal ruled arguments from six parties challenging the project's approval can move forward.

The same court struck down an approval of the project in 2018, saying marine impacts from increased tanker traffic weren't properly considered and that consultation with First Nations was lacking.

Now, it's willing to proceed with a judicial review, but only about whether the second round of consultations with groups like the Tsleil-Waututh were adequate.

"We're happy and we're confident the Canadian constitution protects our rights," said Rueben George of the nation.

However, the Tsleil-Waututh also say the first round of consultations should be considered, and not doing so is a restriction, according to George. He added talks are ongoing with lawyers to see if that can be challenged.

In Alberta, the news landed with a loud thud.

"Well obviously the first thing that went through my mind was disappointment," said the province's energy minister, Sonya Savage.

"We desperately need access to tidewater - we need this pipeline."

Work was halted when investors were spooked by opposition. That led the federal government to buy the pipeline. A federal court decision overturned an original approval, sending the project into turmoil. Ottawa then conducted more analysis of marine traffic and consulted with Indigenous and First Nations before green-lighting the project in June of this year. Construction has just-re-started.

Trans Mountain issued a statement Wednesday saying it was confident in the approvals received thus far, and noting, "as these cases make their way through the courts we will continue with all aspects of planning and construction."

Conservation groups are also deeply disappointed, but for another reason. Ecojustice represents those who'd hoped to have their environmentally-based heard. That didn't happen so they're considering taking the case to the Supreme Court. The court would need to agree to hear it.

"We're deeply disappointed and really concerned that the serious impacts that this project will have on killer whales will go unchallenged," said Alan Andrews, the firm's climate director.

The B.C government is also appealing to the Supreme Court, asking if the province has the jurisdiction to restrict diluted bitumen through the province. A lower court previously ruled against the province.

In a statement, the province's environment minister wrote that it would review Wednesday's decision.

"We believe that we have the authority and the responsibility to defend our environment and economy and we continue to stand up for B.C.'s interests, which is why we have taken our reference case to the Supreme Court of Canada."

The six parties who can move forward with a judicial review can now apply. The court said it hoped the decision could be expedited.