Do presidents have to enforce U.S. laws? Officially, yes. But...

When U.S. President Donald Trump signed an executive order to postpone the banning of TikTok for 75 days, he was ignoring a law, passed just last year, that the platform be sold by its Chinese parent company or be barred in the U.S. on Sunday.

Whether that was legal is debatable. But Trump wasn't the first president to side-step a law, or even to ignore the TikTok ban. Indeed, a day earlier, then-president Joe Biden had said he would leave enforcing the ban to the incoming administration.

But such moves raise questions about whether presidents can disregard laws.

Must presidents enforce laws? 

The U.S. Constitution, in laying out the duties of the president, includes a section under Article II known as the "Take Care Clause" or "Faithful Execution Clause" — stating that the president "shall take care that the laws be faithfully executed." 

"There is not a general authority of the president to simply violate established law," said Phillip J. Cooper, Douglas and Candace Morgan Professor at Portland State University's department of public administration.

"And no, the president is not free from an obligation to take care that the laws be faithfully executed."

The clause is "not an option to say 'I don't like this law and I'm just going to ignore it,'" Saikrishna Prakash, a constitutional law professor at University of Virginia, says in a YouTube explainer video. 

Enforcement is handled by the Justice Department which, as part of the executive branch, answers to the president.

And if the president thinks a law — presumably one that was already on the books, since they can often veto any that arrive on their watch — is ill-conceived? They can ask Congress to amend it.

But, says Prakash, the Take Care clause raises questions including if, for example, a president can ignore a statute they believe to be unconstitutional.

Another complication is the president's discretion to enforce laws.

"The president does have enforcement discretion, in part because that discretion is virtually unavoidable given the enormous scope of federal law," said Ilya Somin, a constitutional law professor at George Mason University.

All sorts of laws have accumulated over the past 200-plus years that aren't strictly enforced  or could possibly enforced except for a small fraction of violators, Somin says. 

Previous presidents have used various tactics with troublesome laws. 

Obama, DACA and DOMA

President Barack Obama came under scrutiny for his handling of immigration laws that he felt were too harsh, after efforts at reform had stalled in Congress. 

Obama issued an executive order in June 2012, known as the Deferred Action for Childhood Arrivals (DACA), saying his administration would stop deporting certain young undocumented immigrants, a move that angered Republicans who claimed it went against the will of Congress.

"He basically said, 'OK, if you're if you're young and you come in for this many years and you do X, Y, Z, then you're here legally. A president cannot legalize someone who is here illegally unless Congress authorized it," said Bruce Fein, a lawyer who specializes in constitutional law.

Politico, back in 2012, noted other laws Obama declined to enforce: He had also instructed the Justice Department to no longer defend the Defense of Marriage Act (DOMA) — which defined marriage as the union of one man and one woman — against court challenges. DOMA had been signed into law, perhaps reluctantly by fellow Democrat Bill Clinton, and was long viewed by Liberals as the brainchild of the Christian right. 

The Justice Department was also instructed to no longer prosecute medical marijuana users and suppliers. 

On education, Obama granted waivers to 10 states, freeing them from the strict requirements of the 2002 No Child Left Behind Act. In doing so, the president removed the mechanism that would force certain school standards to be improved, Politico reported.

George W. Bush and signing statements

Presidents who have taken issue with new laws, or parts of them, have also at times issued "signing statements."

Instead of using their veto power, presidents have instead signed a bill into law, but added one of these official pronouncements, sometimes commenting on how they interpret the law. It may also assert "objections to certain provisions of the law on constitutional grounds," according to the U.S. Library of Congress website.

Such signing statements were once rare, according to the library, but increased gradually over time, becoming increasingly prevalent starting with the Reagan administration in the 1980s.

By 2006, a bipartisan 11-member task force of the American Bar Association wrote a critical report of then-president George W. Bush, accusing him of using signing statements to ignore or not enforce laws passed by Congress.

The task force found that Bush had used more than 800 signing statements to raise constitutional challenges of over 100 laws, more statements than all his predecessors combined.

"The President's constitutional duty is to enforce laws he has signed into being unless and until they are held unconstitutional by the Supreme Court or a subordinate tribunal," panel members wrote. "The Constitution is not what the President says it is." 

Laws that Bush had signed, but also challenged in part included a request for data on the Patriot Act, whistle-blower protections and the banning of U.S. troops from fighting rebels in Colombia, NBC reported at the time.

Most noteworthy perhaps was a ban on torture — a hot-button issue in the wake of 9/11 — that Bush approved but added, in a signing statement, the suggestion that he, as president, could waive the ban in certain circumstances, such an imminent terrorist attack, under his constitutional authority as commander-in-chief.

The Bush administration defended his use of such signing statements, saying he was exercising a legitimate power and raising legitimate questions about the constitutionality of such laws.

But the bar association's task force urged Bush to instead use his veto power if he believed all or part of a bill was unconstitutional, "in keeping with the Constitution's requirement that the president either approve or disapprove in their entirety laws presented to him by Congress."