Nothing in our Constitution says that President Trump can bypass Congress and build a wall by declaring a national emergency. But Congress has passed multiple laws giving extraordinary powers to Trump and to every president. Congress, not the Constitution, is the source of the authority Trump is flirting with using.

Even though Article One of the Constitution gives “all legislative powers” plus control over spending to Congress, lawmakers for decades have delegated those powers to presidents.

When former President Barack Obama announced, “If Congress won’t act, I will,” he at times went beyond even these special laws, so the federal courts ruled he could not bypass Senate confirmation of his nominees and ruled against his Deferred Action for Childhood Arrivals program, or DACA.

The Constitution applies equally to Obama and Trump. But to enlarge our border walls, Trump refers to a law enacted in 1976 and previously used by other presidents. The National Emergencies Act, found in law books at 50 U.S.Code 1601–1651, empowers a president to bypass the usual legislative processes by declaring a national emergency. This catch-all provision replaced hundreds of prior laws whereby Congress gave special emergency authority to the chief executive.

Once he declares an emergency, a companion statute, 10 U.S. Code 2808, says the president can create military construction projects, using funds originally intended for other military projects such as a $10-billion account that Congress approved last September. That money involves the Army Corps of Engineers, with its military and civilian workforce of 37,000 people, which is why a border wall might become a military project.

The law does not specify what qualifies as a national emergency. Instead, its “safeguard” is that Congress can reverse any presidential declaration they disapprove. But undoing a potential Trump declaration likely would require a two-thirds supermajority in both the House and Senate to override a certain White House veto.

As a practical matter, the situation guarantees lawsuits that ultimately would reach the Supreme Court. Justices would need to decide whether Congress can properly expand presidential power so broadly and whether the Supreme Court can and should create restrictions which Congress did not include in the statute.

A border wall bypass would only be the latest symptom of a long-unresolved problem: Members of Congress frequently pass the buck so that presidents decide tough issues rather than accepting responsibility themselves. This practice is the source for multiple recent debates.

Trump’s controversial travel ban was based on a 1965 law that delegated Congress’ constitutional authority over immigration, which the Supreme Court agreed grants broad discretion to Trump and other presidents. His imposition of tariffs, such as on China, uses power granted by Congress in 1962. Obama’s controversial $117-billion-plus nuclear deal with Iran went forward because Congress in May 2015 quietly passed a law saying that whatever he negotiated would stand unless Congress thereafter reversed it. Essentially, they gave Obama a blank check and he could veto any effort to undo it, thus requiring a two-thirds vote to block the Iran deal.

Consistently, presidential actions are not grounded in the Constitution but are using legislative powers delegated to them by a risk-averse Congress, which gripes about decisions but won’t accept accountability.

Whether it involves a border wall, tariffs, or sending money to Iran, the real problem is that Congress evades its constitutional duty to be responsible for all legislation.

There is an answer: halt the delegating and restore separation of powers. Sen. Mike Lee, R-Utah, is leading an effort to fix this, with his Article One Project requiring Congress to make decisions which are its responsibility, and to take the heat for them.

Trump is not usurping power when Congress gave it to him and other presidents. Lawmakers who don’t like how presidents use it should blame themselves.

Former Rep. Ernest Istook, R-Utah, now teaches political science at Utah Valley University.