President Trump hands a pen to then-Sen. Orrin Hatch (R-Utah) after signing a 2017 proclamation to shrink the size of Bears Ears and Grand Staircase-Escalante national monuments in Utah. (Rick Bowmer/AP)

Whether it’s President Trump talking about unilaterally declaring a national emergency to build a wall, or imposing tariffs, or President Barack Obama setting aside land for national monuments in Utah, aggrieved parties always raise the same question: “Who said he could do that?” The answer, usually, is that Congress did.

For more than a century, the “people’s” branch of government has been systematically handing over to presidents powers the framers vested in Congress in the naive belief that each branch would jealously guard its constitutional powers rather than dispense with them.

Presidents, and government agencies, are usually happy to have them.

It’s a form of “collusion,” then-George Mason law professor Neomi Rao wrote in a brilliant 2015 article.

“The conventional view conceives of institutional competition between the Congress and the President — but delegations fracture the collective Congress, allowing for collusion between members of Congress and administrative agencies and eroding the structural rivalry that could check excessive delegations,” Rao wrote.

Rao, a top official in the Trump administration’s Office of Management and Budget, has been nominated for the seat once occupied by Justice Brett M. Kavanaugh on the U.S. Court of Appeals for the D.C. Circuit, where, if so inclined, she could do something about all this.

The losers are anyone attempting to challenge the decisions that flow from these arrangements, especially when the power goes to the president alone, as opposed to agencies.

The courts give special deference to presidents. Unlike the decisions of the average government agency, the rules of the Administrative Procedure Act requiring “reasoned judgments” do not cover presidents who are therefore allowed to make unreasoned judgments.

Laws Congress enacted permitting the president to declare national emergencies — to build a wall, for example — become much harder to overcome, as the Congressional Research Service helpfully pointed out last week, especially when they deploy fearsome trigger words such as “national security” or “military necessity.”

Environmental groups and Native American tribes challenging Trump’s steel and aluminum tariffs are facing such obstacles now in their case currently before the U.S. Court of International Trade.

Congress engaged in a similar giveaway when it enacted Section 232 of the Trade Expansion Act of 1962. Though the Constitution vests authority over trade matters to the legislative branch, Congress offloaded some of it during the Cold War frenzy by authorizing the president “to impose restrictions on certain imports” that “threaten to impair the national security.” Apparently, this was a form of self-intervention: Over the decades, Congress had raised so many tariffs on imports in a frenzy of logrolling that it had to save itself from itself.

As political scientist Todd Tucker wrote in Medium: “It’s powerful stuff. The president gets to decide when and how national security might be under threat. National security is broadly defined to include ‘economic welfare’ and the skills of the workforce. Finally, the president gets to decide the duration and nature of his policy response.”

Trump is now using Section 232 in his “America First” trade war, starting with his imposed tariffs on imported steel and aluminum from the European Union, Canada and Mexico on March 8. The American Institute for International Steel joined others in bringing suit before the trade court, charging that Section 232 “is unconstitutional as an improper delegation of legislative power to the President, in violation of Article I, section 1 of the Constitution and the doctrine of separation of powers and the system of checks and balances that the Constitution protects.” Unfortunately for them, the Supreme Court upheld the section in a unanimous 1976 decision called FEA v. Algonquin SNG Inc.

The courts owe the president “heightened deference,” as the government said in its response to the tariff suit, citing, among other things, the president’s “independent authority in matters of national security and foreign affairs.”

The three-judge panel that heard oral arguments on the case Dec. 19 wondered how Alan Morrison, the plaintiffs' lawyer, could overcome the government’s argument, suggesting, sympathetically, that its hands might be tied.

Congressional generosity is not limited to national security.

Consider Bears Ears and the Antiquities Act, also the subject of ongoing litigation in the federal courts.

The Constitution, Article IV, explicitly gave Congress “the power to dispose of and make all needful rules and regulations respecting the territory and other property belonging to the United States.” But Congress handed it off to the president in 1906, reportedly out of concern about looting of ancient artifacts from public lands.

The resulting Antiquities Act said: “The President may, in the President’s discretion, declare by public proclamation historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest” on government land as national monuments, the only stated limit being that monuments “be confined to the smallest area compatible with proper care and management of the objects to be protected."

Obama used the power to protect millions of acres of land in Utah now called the Bears Ears and Grand Staircase-Escalante national monuments. Many Republicans were outraged. Then-Utah Sen. Orrin G. Hatch, a Republican, called it “executive overreach.” An opinion writer in Forbes, H. Sterling Burnett of the Heartland Institute, labeled it “dictatorial.”

Opponents of Obama’s national monuments in Utah, like Hatch and the energy lobby, did not need to bother with legislation. They had only to wait for a new sympathetic president and Interior secretary. When Trump took office and appointed Ryan Zinke to Interior, among their first actions was shrinking Bears Ears by about 85 percent and the Grand Staircase by about 46 percent so the land can be leased for energy exploration or opened for activities such as motorized vehicle use.

Now conservationists and Native American tribes are in court, challenging Trump’s decision, arguing that the law permits the creation of national monuments but not their reduction by the president.

Obama carved a large chunk of his legacy out of the Antiquities Act, protecting more than 550 million acres, much of it in the form of marine monuments, without having to get a single bill passed, just as Trump imposed his tariffs in the face of significant opposition, including from many congressional Republicans, with whom he did not need to contend.

That helps explain what presidents get from this “collusion.”

But what does Congress get? Scholars have offered lots of reasons for Congress’s yielding to the president and the administrative state, including the ability delegating gives members to avoid responsibility for events in Washington.

That’s where the “collusion” comes into play, suggested Rao, in her paper titled “Administrative Collusion: How Delegation Diminishes the Collective Congress.”

In exchange for giving up collective power, she writes, members gain individual power, as Hatch and other members of Utah’s congressional delegation ultimately did in the case of the national monuments.

She cites, for example, the Affordable Care Act, which gave the Obama administration vast power to grant exemptions. “Immediately after its passage,” she writes, “nearly 20% of exemptions granted were to businesses in House Speaker Nancy Pelosi’s district.”

Instead of laboriously working to legislate on behalf of constituents and/or donors, they can “assert influence” by browbeating the White House and agency officials at hearings or by quietly intervening privately, perhaps just by writing a letter like the “Dingell-grams” to agencies for which the longest-serving member of Congress, former Democratic representative John D. Dingell of Michigan, became famous, Rao suggests, referencing a comment the now-retired congressman made to RollCall in 2013.

“Oversight isn’t necessarily a hearing,” he said. “We find our letters have a special effect on a lot of people.”