It is an old aphorism that means, roughly, that your opinion on matters of power and procedure depends on your position within the political system.
It is important to remember who John Yoo is and was. When George W. Bush decided he wanted to torture terror suspects, he needed some legal papers to cover his ass. He turned to John Yoo to write those legal papers since torture is actually illegal. Yoo's basic position is an extreme version of the theory called the "unitary executive." All executive power is vested in the president. The phrase sounds innocuous, but it isn't. It means that nobody in the executive branch has any independent authority. In Yoo's mind, that means that on matters of national security, the president can make unilateral decisions to do whatever he wants unbound by any other constraints. National security gives the president the ability to do damned near anything, in Yoo's conception.
Keep that in mind as you read through the New York Times editorial in which John Yoo says that Trump is going way too fucking far as president and has no conception of the limits placed on the power of the president by the Constitution. Yoo focuses his harshest attacks on Trump's belief that he can unilaterally withdraw from NAFTA and impose tariffs, which don't invoke Yoo's principles of national security and the unitary executive, but the point is that when you go too far for John Yoo...
I'm a math person, so let's put this in math terms. Put this on a line, representing the tension between Congress and the President. On the left, power is vested more in Congress' hands. On the right, the President's.
John Yoo is way to the fucking right on that spectrum.
And he says that Trump is scaring him by being way to the right of him.
The Constitution is a ridiculously vague document, and I won't get into parsing this stuff. I just want to put this in mathematical context.
Now, contrast Yoo's reaction to congressional Republicans' reactions. Under Obama, the cry was executive over-reach in response to everything. Why? That brings us back to Miles' law. John Yoo, unlike nearly any politician, has an actual, principled stance on executive power. It is that the president has precisely a metric fuck-ton of it. No more, no less. Politicians? It depends on who is in office. If it is their own party? Let him have as much power as he wants.
Miles' law in action. Just remember, though, that John Yoo, whatever you think of him and his opinions on torture, the guy has actual principles on the concept of executive power. Do you? Probably not.