As recently as one year ago, the Supreme Court’s Republican majority was determined to reduce executive power.

Joe Biden, a Democrat, was in the White House, and the Republican justices were very concerned that the executive branch was claiming “highly consequential power beyond what Congress could reasonably be understood to have granted.” To keep the executive in check, the Republican justices invented a legal doctrine, known as “major questions,” which was supposed to prevent the president or his subordinates from enacting new policies with “vast ‘economic and political significance’” — at least without getting very specific authorization from Congress first.

Flash forward to the present, and these same Republicans are about to reveal whether this major questions doctrine was an honest effort to allocate power among the three branches of US government, or whether it was simply something they made up to stymie a Democratic president from enacting his agenda.

On November 5, the Supreme Court will hear oral arguments in two cases — Learning Resources v. Trump and Trump v. V.O.S. Selections — both of which challenge the ever-shifting tariffs that Trump has imposed on US imports.

In both cases, the challengers argue that various provisions of the International Emergency Economic Powers Act of 1977 (IEEPA), the law Trump relied upon when he instituted his tariffs, do not actually permit those tariffs to exist. Several of these statutory arguments, as numerous federal judges have now concluded, are quite strong.

But it’s the Republican justices’ major questions doctrine that should remove any doubt that Trump’s tariffs are illegal. According to the center-right Tax Foundation, Trump’s tariffs “are the largest US tax increase as a percent of GDP (0.55 percent for 2025) since 1993.” The Tax Foundation estimates that they will “raise $2.9 trillion in revenue over the next decade on a conventional basis and reduce US GDP by 0.7 percent” — and that’s not counting the money Americans are losing because other countries respond to US tariffs by imposing similar trade barriers on the United States.

The tariffs, in other words, are clearly a matter of “vast economic and political significance.”

Trump’s tariffs also appear to divide more traditional, fiscally conservative Republicans from the president’s MAGA loyalists.

One of the primary lawyers challenging the tariffs is

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