President Trump speaks in the Rose Garden about his emergency declaration Friday. (Jim Lo Scalzo/EPA-EFE/REX/Shutterstock)

Danielle Allen is a political theorist at Harvard University and a contributing columnist for The Post.

During the 1788-1789 ratification debates for the Constitution, one particularly sharp concern among voters was whether, by creating the office of president, the Constitutional Convention had delivered a monarch, landing the Americans right back where they had started with mad King George.

Are we there yet?

No. But with President Trump’s declaration of a national emergency we have taken another significant step in that direction.

In Federalist No. 69, Alexander Hamilton responded to this worry about the Constitution as Trojan horse for monarchy by listing nine factors that distinguish the president from a British sovereign:

(1) The President of the United States would be an officer elected by the people for FOUR years; the king of Great Britain is a perpetual and HEREDITARY prince.

(2) The one would be amenable [through impeachment] to personal punishment and disgrace; the person of the other is sacred and inviolable.

(3) The one would have a QUALIFIED negative upon the acts of the legislative body [through a veto defeasible with a two-thirds vote]; the other has an ABSOLUTE negative.

(4) The one would have a right to command the military and naval forces of the nation; the other, in addition to this right, possesses that of DECLARING war, and of RAISING and REGULATING fleets and armies by his own authority.

(5) The one would have a concurrent power [through advice and consent] with a branch of the legislature in the formation of treaties; the other is the SOLE POSSESSOR of the power of making treaties.

(6) The one would have a like concurrent authority in appointing to offices; the other is the sole author of all appointments.

(7) The one can confer no privileges whatever; the other can make denizens of aliens, noblemen of commoners; can erect corporations with all the rights incident to corporate bodies.

(8) The one can prescribe no rules concerning the commerce or currency of the nation; the other is in several respects the arbiter of commerce, and in this capacity can establish markets and fairs, can regulate weights and measures, can lay embargoes for a limited time, can coin money, can authorize or prohibit the circulation of foreign coin.

(9) The one has no particle of spiritual jurisdiction; the other is the supreme head and governor of the national church!

Now, “in the year of our Lord two thousand nineteen, and of the Independence of the United States of America the two hundred and forty-third,” to quote Trump’s emergency proclamation, we must acknowledge that on points four, five and eight, the original constitutional limitations on the presidency have seriously eroded.

With regard to treaties, in the years from 1789-1839, 69 percent of U.S. agreements with foreign states were treaties, according to law professors Curtis Bradley and Jack Goldsmith. In recent decades the number has been around 6 percent, and agreements are now generally made by means of executive agreement, as with the Paris climate agreement. This movement in the direction of executive power has been underway across the 20th century and constantly accelerating.

On money and commerce, the creation of a national bank system and then the Federal Reserve, changed the dynamic in broad terms. More recently, Trump has entered into freewheeling executive imposition of trade tariffs by relying on a 1962 piece of congressional legislation, the Trade Expansion Act, which permits the executive branch to evaluate the impact of imports on national security and to respond with tariffs.

On the fourth point, in the 1976 National Emergencies Act, Congress gave the president broad authority to declare an emergency. Although every president since has mainly used that authority to impose sanctions in domains pertaining to foreign policy, Trump has assigned the execution of his declaration to the secretary of defense, effectively making this a military action. President George W. Bush is the only prior president to have used the authority for military action, which he did in the wake of Sept. 11 — a moment of urgency that required decision-making at a speed greater than that achievable through congressional deliberations.

The health of our political system now comes down entirely to the popular election of the president and to congressional oversight of the executive in the form of advice and consent on appointments, supermajority veto overrides and impeachment processes. No wonder discussion of appointments and impeachment dominates our political conversation.

When Congress ceases to have any meaningful authority in relation to the president, the only check on a president’s behavior will be elections every four years. The result of this will be whipsawing changes back and forth between the preferences of one or another charismatic leader capable of mesmerizing enough of the population. Congress is supposed to be a mediating and moderating branch, with the Senate as the ultimate rudder of the polity, since it is the only legislative or executive branch that does not turn over every fourth year. But Congress can achieve consistency of policy direction for the country, only if it can serve as a meaningful check on the executive.

In the current “emergency” concerning border security, there was time for Congress to act, and Congress acted, achieving a worthy compromise. Against a backdrop of adequate time for congressional deliberation and decision, an emergency declaration is unreasonable and disregards the Constitution’s preference for legislative decision-making wherever possible.

Congress needs to roll back the erosion of its authority, first and foremost by revisiting the National Emergencies Act and amending it to rebalance away from executive flexibility in the direction of legislative authority.

Congress did its job on a border security compromise, thank heavens. It’s time to do it again by amending the 1976 act.