President Trump’s repeated attempts to impose tariffs have become an encapsulation of his second term. They have hurt the American economy and his own popularity. They also range from legally dubious to blatantly illegal. With Mr. Trump now engaging in a trade war with Canada — which has decided to stand up to his bullying — we want to step back and explain both the economic and the legal damage from his tariffs. We also urge Congress and the courts to take action and stop this madness.

The tariffs offer a signature opportunity for the other two branches of the federal government to insist that Mr. Trump abide by the Constitution and stop punishing American workers and consumers. The Supreme Court has already rejected most of Mr. Trump’s tariffs once. In February, it ruled them to be illegal, and he immediately made clear that he would not be deterred. “Their decision is incorrect,” he said within hours of the ruling’s release. “But it doesn’t matter.”

It is true that other presidents have at times taken a similarly combative approach to a Supreme Court decision. They have abandoned policies that the court rejected and enacted alternatives that tried to accomplish the same goals in different ways. Only a few years ago, President Joe Biden did so with student debt. “The Supreme Court blocked me from relieving student debt,” Mr. Biden said. “But they didn’t stop me.”

Still, Mr. Trump’s defiance stands out. He has twice tried to circumvent the court’s tariff ruling, imposing new rounds of import fees by invoking legal justifications that are patently ridiculous. This is part of a broader pattern, in two ways. First, he has tried to get around court rulings far more often than his predecessors. With lower courts, he has openly flouted judges’ decisions, including in January, when he violated nearly 100 court orders related to immigration. With the Supreme Court, he has been more respectful but has still engaged in “legalistic noncompliance,” as the scholars Daniel T. Deacon and Leah M. Litman have written.