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President Donald Trump is giving the country a crash course in the use of executive orders. He's signed them so frequently, and with such flourish, and on such a wide array of issues, that it can seem as if he's found some new method to exert power.

But that's not so.

Executive orders are as old as the republic itself. They don't show up in the Constitution, but their unilateral use has been upheld by the Supreme Court. And there aren't many ways to try to stop a president from enforcing one.

"The fact is that each administration, beginning at least with Clinton and really since Roosevelt, has opened with a flurry of executive orders by presidents wanting to make their mark to show they're accomplishing something fast, which is very difficult to do through Congress," said Stephen Griffin, who teaches constitutional law at Tulane University Law School.

The most common way to challenge an order is argue a violation of people's rights. Trump is facing legal challenges over his order imposing temporary restrictions on those entering the U.S. from seven Muslim majority countries, and curtailing funding for “sanctuary cities.”

Related: Federal Judge Temporarily Blocks Trump Immigration Order

Trump’s orders have targeted a range of issues, from immigration to economics to health care to oil production. But in terms of volume, his executive orders aren't all that extraordinary.

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And he's signing them at a pace that isn't much different from that of President Barack Obama, who was also accused by critics of overstepping his authority.

Executive orders are one of three types of executive actions, the other two being memos and proclamations. Trump has signed 22 executive actions but only eight executive orders. Phil McCausland

The uproar that follows executive orders typically reflects the country's divisive politics, Griffin said.

"A lot of this angst over executive orders is displaced angst over Trump getting elected," he said.

He added: "People underestimate just how much discretionary power the Constitution gives the president."

Every president since George Washington has exercised his power to issue executive orders, which are published in the Federal Register and create new policies or direct agencies to act in a certain way. Orders are one of three types of executive actions, the other two being memos and proclamations, which generally carry less weight.

"They happen all the time, and it's the unusual cases that get a lot of notoriety," said Michael Gerhardt, the National Constitution Center's scholar-in-residence. "Executive orders are often mundane and routine, but are sometimes quite dramatic."

Related: Trump Named in More Than 50 Lawsuits Since Inauguration

The most famous executive orders include Abraham Lincoln's Emancipation Proclamation, Franklin D. Roosevelt's creation of Japanese internment camps, Harry Truman's desegregation of the armed forces and Dwight Eisenhower's use of the Arkansas National Guard to enforce integration of Little Rock schools.

Roosevelt holds the record for executive orders, with 3,728 over a period that covered the Great Depression and World War II, according to the National Constitution Center. By comparison, Obama issued 277, George W. Bush issued 291 and Bill Clinton issued 364.

The power to issue executive orders doesn't show up explicitly in the Constitution or federal law. But it has been interpreted as an extension of Article II of the Constitution, which grants the president authority to “take care that the laws be faithfully executed.”

Congress can pass laws that give presidents additional powers. It can also pass laws that override executive orders. Such measures are subject to a presidential veto, however, so they are attempted much less frequently than lawsuits.

Truman faced the toughest challenge, which culminated with the Supreme Court invalidating an order that put steel mills under government control during a strike in the middle of the Korean War. In that case, the justices ruled, the president overstepped authority by enacting what was in essence, a new law — something only Congress can do.

Executive orders are by nature unenduring because they can be revoked or rewritten by successors.

That, scholars say, explains why the highest volume of executive orders tend to come when an administration of one political party takes over from that of another — such as Trump, a Republican, replacing Obama, a Democrat.

Griffin compared the presidency to being the captain of an ever-growing ship, built by the Constitution and fitted out over more than two centuries of laws.

"Presidents can steer the ship almost anywhere they want to go, unless they perhaps propose to violate a specific provision of the Constitution," he said. "The ship was built mostly by Congress, but it still is an amazingly big and powerful ship. If the previous administration steered it left, they can steer the ship right."