Ben Shapiro, arguing against the use of emergency powers to fund the border wall, says this:

Proponents of President Donald Trump would like to see power centralized in the presidency; antagonists of Trump would like to see power centralized in the FBI.

Trump’s allies seem eager for Trump to declare a national emergency in order to appropriate funds for a border wall….

It’s good that the legislative branch checks the executive branch, and it’s good that the executive branch must remain in control of executive branch agencies.

Here’s the easy test: How would you feel if the situations were reversed?

I must note, first, that Shapiro badly overstates the case when he asserts that Trump’s proponents ” would like to see power centralized in the presidency,” and that “antagonists of Trump would like to see power centralized in the FBI.” Trump’s proponents would like to see power exercised responsibly, and most of the Democrats in Congress (as well as many Republicans) routinely fail to do that. Refusal to fund the border wall, merely to thwart Trump, is just a current and egregious example of that failure. Those same Democrats want the FBI to have power only when it comes to Trump; otherwise, they would prefer to emasculate the FBI. Democrats’ embrace of the FBI is a matter of political convenience, not principled conviction.

Now for the fallacy, which is implicit in Shapiro’s question, “How would you feel if the situations were reversed?” That question implies the following syllogism:

It is bad for the executive to use emergency powers.

The use of emergency powers is dictated by precedent.

Therefore, if Trump desists from using emergency powers, a future president (even a Democrat) will also desist and thereby avoid doing a bad thing.

The syllogism is logically valid, in that the conclusion follows from the premises. But the conclusion is arguably false because a Democrat — an Obama, for instance — is unlikely to be swayed by precedent in the matter of emergency powers.