A U.S. federal appeals court in Washington, D.C. has ruled that most of the tariffs imposed by President Donald Trump were “illegal.”

The court said the International Emergency Economic Powers Act, which Trump cited as the legal basis, does not give the president authority to impose tariffs.

The judges added that when Congress passed the law, it never intended to hand the president unlimited tariff powers.

Trump blasted the decision as “politically biased,” writing on social media that all tariffs remain in effect. He warned that lifting them would be a “total disaster” for the nation and signaled plans to appeal to the Supreme Court.

The case covers tariffs Trump imposed earlier this year on China, Canada, Mexico, and other countries. However, duties on steel and aluminum are not affected by the ruling.