"What’s unspoken in Vance’s tweet is the well-established power of courts to police the limits of that discretion, i.e., to decide which exercises of power by the executive branch are, in fact, 'legitimate.'"

"Thus, there are examples of courts interfering in military operations—granting habeas petitions to individuals in military custody; blocking military commission prosecutions; and even, during the Biden administration, blocking the military’s COVID vaccination mandate as applied to certain active-duty troops. There’s even a single example of a federal judge blocking an active military operation—Judge Judd’s July 1973 injunction against President Nixon’s bombing of Cambodia.... That ruling might have been wrong; it certainly wasn’t 'illegal.'... calling a judicial decision 'illegal' certainly sounds like a basis for refusing to abide by it—especially if one believes... that such rulings are 'a violation of the separation of powers.' The proper remedy, of course, is to appeal a decision you believe is wrong. And if the Supreme Court, the federal court of last resort, reaches the 'wrong' decision, there are legal ways to seek to overturn it; refusing to follow it isn’t one of them. But the reality is that there is no history or tradition in this country of presidents ignoring judicial rulings on the ground that they are 'illegal.'..."

Writes lawprof Steve Vladek in "What Vice President Vance Did—and Didn't—Say About Judicial Power" (Substack).

Here's the JD Vance tweet under discussion:

If a judge tried to tell a general how to conduct a military operation, that would be illegal.

If a judge tried to command the attorney general in how to use her discretion as a prosecutor, that's also illegal.

Judges aren't allowed to control the executive's legitimate power.