This past week, the United States Court of Appeals for the Federal Circuit — which sits right below the Supreme Court — is hearing a case of profound constitutional importance. It is the government’s appeal of a ruling by the U.S. Court of International Trade, which found that President Donald Trump’s unilateral imposition of tariffs on certain goods entering the United States from certain foreign countries is unconstitutional.

The lower court recognized that the Constitution established the separation of powers and gave the taxing power exclusively to Congress.

Here is the backstory.

The Constitution’s structure separates powers among the three branches and articulates their core responsibilities. Congress writes the laws in areas of governance delegated to it. The president enforces the laws faithfully. The courts interpret the laws and the Constitution.

Since that pronouncement in a case called Marbury v. Madison (the same James Madison who wrote the Constitution) in 1803, it has been the province of judges to decide what the laws mean and if they conform to the Constitution. In 1803, the sole province of judges had been to resolve disputes properly before them.

The Marbury case crafted the concept of judicial review — the power of courts to review and to void the official acts of the other two branches in cases properly before them — and it has been accepted ever since.

Now back to the Constitution.

Two clauses of the Constitution are relevant for our discussion here, and both appear in Article I, which establishes the Congress and articulates its powers. At the outset of the article, it declares that “All legislative Powers herein granted shall be vested in a Congress of the United States.” The second clause, also in Article I, is the very first power granted to Congress. “Congress shall have the Power To lay and collect Taxes … ”

Taken together, these two clauses unambiguously manifest the constitutional understanding and mandate that taxes are exclusively a congressional function.

Tariffs have been a part of the nation’s history since colonial days..

Trump has attempted to upset this well-settled law.

The first is that tariffs are not a tax because they only apply to the origin of certain goods from certain countries. Thus, the feds argue, Trump’s tariffs don’t apply to all automobiles or toasters, just those made in foreign countries. And even if tariffs are taxes, they are paid by foreigners. From this it follows, the feds argued, that tariffs are an instrument of foreign policy, and thus immune from judicial scrutiny. The third argument is that Congress gave away some of its taxing powers to the president when it enabled him to address economic emergencies.

The lower court dispatched these silly arguments quickly. Tariffs are a sales tax, paid by the foreign manufacturer and passed on to the American consumer. Second, the president’s primacy in foreign affairs is tempered by numerous clauses in the Constitution, from war-making to Senate confirmation of ambassadors to his obligations to honor personal liberties. Since ALL legislative powers were granted to Congress and core among them is taxation, only Congress can impose tariffs no matter how they are collected.

There was a time when Congress maintained independence and steadfastly guarded its constitutional prerogatives.