Here’s how powerful an executive order is and how it could be reversed

President Trump has signed 19 executive actions since he took the oath of office on January 20th. The orders and memoranda range from freezing all pending regulations until his administration approved them, to a controversial immigration order barring citizens and refugees from seven Muslim-majority nations from entering the US.

It’s been a dizzying first week and a half of the Trump administration, as federal agency employees, reporters covering the White House, and casual observers alike navigate through the 45th president’s flurry of executive orders.

What is an executive order?

An executive order is a “directive by the president to the officers and officials of the executive branch,” Columbia law professor and former Associate Counsel to President Jimmy Carter, Philip Bobbitt told Business Insider.

While the president can’t order private citizens to specifically do something, they are still affected by executive orders insofar as their interactions with executive officials. “They do have the effect of law,” Bobbitt explained.

Can an executive order be reversed?

Both the legislative and judicial branches have the power to reverse an executive order.

If the president issues an executive order in accordance with a law passed by the legislative branch and Congress disagrees, they can pass a bill clarifying the law. However, the president has the power of the veto, in which case Congress would have to override the veto with a two-thirds majority in both the House of Representatives and the Senate.

If, however, an executive order pertains to the president’s independent constitutional responsibilities, then only the courts can reverse it. Bobbitt uses the example of Emancipation Proclamation, an executive order issued by Abraham Lincoln in accordance with his power as commander-in-chief. While Congress did not have the power to override that order, the courts could have declared it unconstitutional.

More recently, the courts blocked President Obama’s 2014 executive action to shield millions of undocumented immigrants from deportation and allow them to work legally in the US. The 2016 Supreme Court decision was deadlocked (only eight justices voted as there was a seat left vacant by Justice Scalia’s death earlier that year). The tie meant that a lower court’s decision that Obama likely exceeded his executive authority stopped the plan from being implemented.