(CN) — The Supreme Court of Canada, in a pivotal victory for Prime Minister Justin Trudeau’s climate policy, has ruled that the government’s decision to mandate a national carbon price to reduce greenhouse gas emissions is constitutional.

In a split 6-3 decision issued Thursday morning, Canada’s highest court ruled in favor of the nation’s federal government following a hotly contested legal battle over the government’s decision to impose a minimum fuel charge on all distributors and producers of carbon-based fuel in the country. The move, approved by parliament in 2018, received immediate pushback from a number of Canada’s provinces who claimed the decision was a blatant overreach on behalf of the government and argued that such decisions fall solely under their provincial authority.

These challenges resulted in a lengthy court battle, numerous appeals and conflicting rulings before ultimately landing at the feet of the Supreme Court, which has now definitively found that the decision to issue the carbon price was legal.

Chief Justice Richard Wagner, writing for the majority, said that at the heart of the legal battle rests the stark reality that climate change is a very real threat to the safety and wellbeing of humanity.

“Climate change is real,” Wagner wrote in Thursday’s ruling. “It is caused by greenhouse gas emissions resulting from human activities, and it poses a grave threat to humanity’s future. The only way to address the threat of climate change is to reduce greenhouse gas emissions.”

Because the threat of climate change is so severe, Wagner says, the gravity of the problem gives the government authority to act under the “peace, order and good government” clause of the Canadian Constitution. The clause, commonly referred to as the POGG clause, is rarely successfully cited as the basis for governmental action but does nonetheless give federal leaders the authority to act on issues that relate to the entire nation.

Wagner says this is where Trudeau’s carbon price prevails. While the provinces — namely the more conservative or oil-centric Alberta, Ontario and Saskatchewan areas — claim that managing natural resources to combat climate change is something they can do independently, POGG can be activated when there is a clear inability on behalf of all the provinces to come together and fix the problem themselves.

The chief justice says that allowing provinces to handle this on their own would only hold Canada back from combating climate change as a collective nation. Even if the majority of provinces were able to coordinate their efforts, it would only take a small number of provinces unwilling to impose a minimum carbon price to undermine the actions of the rest of the country.

The ruling states that only though a national and unified approach, in which all provinces are bound to playing by the same carbon pricing rules, does Canada have a chance at successfully reducing its carbon footprint.

The judge notes that provinces are still allowed to regulate themselves when it comes to their carbon pricing systems and can still chose their own regulatory frameworks when it comes to emissions standards. All they have to do is comply with the minimum standards laid out by the federal government or else they risk being slapped with an increased carbon tax.

Wagner also notes that carbon pricing works. The justice writes that there is a “”broad consensus among international bodies” that setting these minimum prices can significantly cut back on greenhouse emissions from carbon, with the idea being that the more carbon costs the less people will actually use it.

The ruling’s mention of an international consensus regarding the effectiveness of carbon pricing methods could have some possible implications for other nations that are considering similar measures. Implementing a carbon pricing system in the United States for instance, has often been cited as crucial step in overhauling America’s energy policies, but has so far failed to get off the ground.

Thursday’s ruling officially gives Trudeau’s climate policy the ability to forge ahead with imposing minimum carbon prices, which will continue to rise throughout the next decade to further discourage carbon use. The minimum price is currently set at $30 per 1.1 ton of emissions, but the government says it will continue to rise the minimum over the next few years before it ultimately hits $170 per 1.1 ton of emissions by 2030.