One day, the Democrats complained that Supreme Court nominee Brett Kavanaugh lacks sufficient deference to the executive, that he could “ could cripple the next Democratic president.”

The next day, they flipped and complained that he would expand presidential powers too much. “If Judge Kavanaugh is confirmed,” the absurd Democratic witness, John Dean, said, “I submit we will have the most pro-presidential powers Supreme Court in the modern era.”

Which one is it? Is Kavanaugh a threat to the power of the presidency, or will he unleash presidential power?

These seemingly contradictory criticisms are easily reconciled in an understanding that Kavanaugh believes the president is constrained by the Constitution and by statute, and that Congress is there to check his power. Democrats believe the president ought to be constrained by the bureaucracy, and not so much by the law or the Constitution.

The relevant authorities on this are two clauses in the Constitution: The beginning of Article I and the beginning of Article II.

Article I begins, “All legislative powers herein granted shall be vested in a Congress of the United States.” One implication is that no legislative power is vested in the executive branch. Therefore, a president may issue rules or regulations only to implement the laws passed by Congress.

For instance, President Barack Obama’s “Clean Power Plan,” regulating greenhouse gases from power plants, was plainly a case of the executive branch making laws that Congress had rejected. The White House tried to defend the program by arguing that the executive branch should be given broad deference in how it interprets the law.

The precedent involved was the Chevron case, and Obama was appealing to so-called Chevron deference. Kavanaugh’s jurisprudence suggests he believes that administration actions should be prescribed by law. The Left often wants to allow the executive to do anything that it can be argued that the law might suggest.

With too much deference to the executive, Kavanaugh has written, “agencies can stretch the meaning of statutes enacted by Congress to accommodate their preferred policy outcomes.”

Adding Kavanaugh to the high court could result in an executive branch less able to make its own law. Liberals should like that, shouldn’t they?

Instead, liberals worry that “Without Chevron deference, agencies could end up lacking the tools to deal with modern problems,” as liberal writer Pema Levy wrote in an article at Mother Jones.

Meanwhile, Democrats brought in their favorite disbarred ex-felon cover-up artist, John Dean, to testify that Kavanaugh is too “pro-presidential powers.”

It’s confusing, until you realize what powers Dean is talking about. He’s not worried about the president’s war-making powers, or policy-making powers. He’s worried about the president’s control over the rest of the executive branch.

Kavanaugh adheres to the idea of the “unitary executive.”

Article II of the Constitution begins, “The executive power shall be vested in a president of the United States of America.” Kavanaugh takes that to mean that the executive power shall be vested in the president of the United States of America. Dean and his Democratic friends somehow take that to mean the executive power shall be vested in plenty of other people, too.

The unitary executive theory — that is, the actual Constitution — sees all Cabinet officials, all bureaucrats, and employees of executive agencies as agents of the president.

This upsets the Left, because it wants the bureaucracy to be a sort of fourth branch of government. People on the Left want unelected career government employees to wield power without permission of the president. An independent, powerful, unaccountable bureaucracy would be good for the Left’s agenda of expanding government and advancing liberal social and economic policy.

Specifically, Dean and the Democrats want more power to prosecute a president in court. Here, again, the Constitution has other ideas. It is up to Congress to try or convict the president, through impeachment. This gives too much power to elected politicians for the Democrats’ liking.

So Kavanaugh on the court could result in a presidency limited by the Constitution and by Congress, but not by the unelected bureaucracy.

That sounds very much like what we want.