BATTLE OVER THE BORDER WALL: What you need to know about the legal showdown over the president's national emergency Declaration.

• Author: Smith, Patricia
• Position: NATIONAL

On February 15, President Trump declared a national emergency to fund the construction of a 1,000-mile wall on the border with Mexico after Congress provided money for only a sliver of the project.

The announcement came as the president signed a spending deal negotiated by Democrats and Republicans in Congress that included $1,375 billion for border fencing, but not the $5.7 billion Trump had been demanding for construction of a much longer wall. The agreement headed off what would have been the second shutdown of the federal government in the space of a month over the issue. But Trump's declaration prompted lawsuits that set up a constitutional showdown over the separation of powers and the president's authority.

Here's what you need to know to understand the battle over the emergency declaration.

What's the conflict about?

Since December, Trump has been asking for $5.7 billion to build a wall along the southern border. About 650 miles of the 2,000-mile-long border between the U.S. and Mexico already have some kind of barrier (see graphic). Building a wall along the entire border was a key campaign promise--something Trump said would stop the flow of undocumented immigrants and illegal drugs into the U.S.

Trump's insistence on billions for the wall after Congress refused to allocate it led to a government shutdown that began in late December and lasted a record 35 days, forcing some 800,000 federal employees to go without their paychecks.

In response to Trump's emergency declaration, 16 states, including California and New York, filed a lawsuit arguing that the president doesn't have the authority to divert funds for constructing a wall along the Mexican border because Congress controls federal spending.

What's a national emergency?

Congress has enacted laws that permit the president, upon declaring a national emergency, to take steps that would normally be forbidden by law. The idea is to allow the executive branch to move quickly in emergency circumstances.

The National Emergencies Act of 1976 gives the president broad authority to decide whether an emergency exists. Presidents have used this law to declare emergencies about five dozen times. But most of those cases dealt with foreign crises and involved freezing assets or blocking trade or exports, not redirecting money without congressional authorization.

White House officials cite two times that such emergency declarations were used by presidents to spend money without legislative...