An impending case before the Supreme Court could end up granting President Donald Trump “sweeping fiscal authority” that has historically been held exclusively by Congress, a precedent that, once set, could expand the power of the executive branch indefinitely.

That case is related to Trump’s tariffs, which were ruled illegal and blocked by a federal court last month. Trump fought for the Supreme Court to take up the matter, a wish that was ultimately granted on Tuesday after the court agreed to hear the Trump administration’s case in November.

Now, on the eve of that case being taken up and decided upon, one commentator is sounding the alarm that the court’s decision could end up undoing the American system as imagined by the framers of the Constitution.

“The Constitution grants Congress authority over both taxes and tariffs,” wrote commentator Greg Ip in an analysis published in the Wall Street Journal Wednesday.

“This was central to the framers’ systems of checks and balances. James Madison argued that the president couldn’t become king because the ‘purse is in the hands of the representatives of the people.’”

The authority to impose tariffs has historically been held by Congress, which under Article I of the Constitution, limits government spending to acts of law, which only Congress may enact. This standard has been softened, however, over the past century, with new laws granting limited power to the executive branch to enact tariffs, largely as a tool to coerce or punish foreign nations, and not to generate revenue.

Trump, however, has openly characterized his sweeping tariff policy as a revenue builder, while in the courts, arguing it to be a matter of national security.

If Trump gets his wish, Ip warned, not only would his authority to impose sweeping tariffs be cemented, but it could also be argued that Trump – or subsequent president – could impose taxes on Americans of any kind.

“There would also be no end to uncertainty,” Ip wrote. “...And then there are all the other taxes, besides tariffs, Trump could feel free to use.”

John Brooks, a professor of tax law at Fordham University, concurred with Ip’s assessment, telling Ip that if the Supreme Court were to rule in Trump’s favor on tariffs, there was no reason to believe his newfound authority wouldn’t extend to domestic taxes.

“Any tax with foreign-policy implications would be within his authority,” Brooks said, speaking with the Wall Street Journal. “Why wouldn’t that apply to any tax he can conceive of, not just the tariffs?”