Despite a ruling from the Supreme Court that concluded the law is largely unconstitutional, Environment Minister Steven Guilbeault says the federal government is sticking by its controversial Impact Assessment Act (IAA).

Guilbeault said Thursday the Liberals will not repeal the legislation — as some Conservative MPs have demanded — and will instead make changes to "align" the law with the top court's ruling.

"The Supreme Court reiterated the fact that federal government can and should be doing impact assessment," Guilbeault told a press conference Thursday. "It gave us guidance in terms of where we needed to course-correct and that is what we will be doing."

On Oct. 13, the Supreme Court ruled that sections of the federal Impact Assessment Act are unconstitutional. Some parts of the law were found to be within federal jurisdiction, but the court said other sections were too broad.

Guilbeault offered no timeline for tabling and passing amendments addressing the court's concerns. He hinted that it will take "months."

"There is a need to move swiftly and we will be focusing on that in the coming months," he said.

On Wednesday, his office issued interim guidance on the law for project proponents and the federal Impact Assessment Agency of Canada (IAAC) until the legislation is revised.

According to a government guidance document, the environment minister's discretionary authority to conduct assessments of projects has been paused. Those powers will resume only once the amendments take effect, says the guidance document.

Current project assessments will continue, the document says, and the IAAC will provide opinions on whether proposed projects fall under federal jurisdiction. The agency also can determine "whether a full impact assessment" of a project "is warranted," the guidance document says.

Guilbeault said 23 projects are currently being assessed, all in their "early stages."

The IAAC confirmed it will continue its work on Ring of Fire projects in Ontario and offshore wind turbine projects in Nova Scotia and Newfoundland and Labrador, saying the work will help the agency better understand the impacts of these proposed developments.

"We don't want this federal adjustment to cause delays down the road," Guilbeault said.

The IAA, previously known as Bill C-69, allows federal regulators to consider the potential environmental and social impacts of various resource and infrastructure projects. It was enacted in 2019.

The IAA has long been controversial among conservative politicians in Alberta, including former premier Jason Kenney, who frequently referred to it as the "no more pipelines act."

Writing for the majority in a 5-2 decision, Chief Justice of the Supreme Court of Canada Richard Wagner said the processes set forth in Sections 81 to 91 of the IAA were constitutional and could be separated out.

Those sections involve projects carried out or financed by federal authorities on federal lands, or outside Canada, and therefore fall under federal jurisdiction. Those provisions were not challenged as unconstitutional.

However, Wagner wrote that the balance of the scheme, involving "designated projects," was unconstitutional.

In a media statement, Alberta's Environment Minister Minister Rebecca Schulz repeated calls for the government to repeal the legislation and said the new guidance creates more uncertainty.

"The federal government's failure to accept the Supreme Court of Canada's opinion that the Impact Assessment Act is unconstitutional and abandon this bad act is causing unnecessary confusion across Canada," Schulz said. "This interim guidance does not help reduce confusion – it only adds to it."

At least one environmental group, Environmental Defence, supported the government's move Thursday to amend the legislation.

"We are pleased the government is committing to amend the Impact Assessment Act to ensure that its protections remain in place while complying with the Supreme Court of Canada's decision," said Environmental Defence's Ontario environment program manager Phil Pothen.

The NDP, which opposed the legislation when it was before the House in 2018, said it is willing to work with the Liberals on improving it.

"From the beginning, New Democrats had serious concerns with the Liberals' environmental assessment law," the NDP's environment and climate change critic Laurel Collins said in a media statement. "We're going to push the Liberals to make sure that the amendments needed to fix the law and protect the environment are brought forward quickly."

The Conservatives, on the other hand, are promising to drop the law entirely, arguing it drives investors away.

"Conservatives will scrap Bill C-69, streamline red tape, reduce permitting timelines, and cut the carbon taxes so the private sector can build major projects, create jobs and expand traditional and renewable resource development and exports," Conservative natural resources critic Shannon Stubbs said in a media statement.