Here's why California and 15 states sued Trump after his national emergency declaration to build the wall

California and 15 other states sued President Donald Trump in federal court on Monday, questioning the president’s authority to declare a national emergency in order to access funds to build a border wall just three days after his Friday declaration.

At issue is whether the president of the United States or Congress controls these federal funds.

The legal clash was expected — even Trump said he saw it coming himself when he declared his national emergency at a Friday news conference outside the White House. Now that it’s happened, here’s what you should know about the lawsuit, starting with which states are suing the Republican president and whether they all have Democratic governors. Spoiler alert: They don’t.

Related: Trump can call a national emergency, but can he use one to build a border wall?

(You can read the full text of the lawsuit filed in Federal District Court in San Francisco here.)

Which states are suing Trump?

These 16 states are suing Trump:

1. California
2. Colorado
3. Connecticut
4. Delaware
5. Hawaii
6. Illinois
7. Maine
8. Maryland
9. Michigan
10. Minnesota
11. Nevada
12. New Jersey
13. New Mexico
14. New York
15. Oregon
16. Virginia

Do all of the states have Democratic governors?

No. Maryland has a Republican governor, but it has a Democratic attorney general.

What are the states arguing in suing Trump?

The states are making three main arguments in this case:

1. Trump’s emergency declaration is unfounded, given the president’s own admission that it was not necessary.
2. Trump is misusing his national emergency powers to “redirect federal dollars appropriated for drug interdiction, military construction, and law enforcement initiatives toward building a wall on the United States-Mexico border. This includes the diversion of funding that each of the Plaintiff States receive.”
3. Use of those funds to build the wall goes against Congress’ intent, an action the state say is unconstitutional.

What does the Constitution say about this?

The Constitution grants Trump the authority to declare a national emergency, and it allows him to divert some military funds to for construction projects.

Specifically, two sections of the U.S. Code — Title 10, code 2808 and Title 33, code 2293 — may give Trump the power to direct the Secretary of Defense to use military funds for construction projects and to divert the Army’s civil works program resources.

So cut to the chase: Who will win this case?

California Attorney General Xavier Becerra has called it a “fake national emergency” on Twitter and has said that the best evidence of this is Trump’s own words.

“I didn’t need to do this, but I’d rather do it much faster,” Trump said on Friday when he made the official declaration.

But the biggest sign that the courts may stop Trump’s emergency declaration came from his own justice department. Ahead of that declaration, ABC News reported that the Department of Justice warned the White House that the emergency declaration was certain to be blocked by the courts, at least temporarily.

At his news conference, Trump said he would probably get a couple bad rulings before the case winds up in the Supreme Court, where he’d win. He said, "We will have a national emergency. And we will then be sued, and they will sue us in the 9th Circuit, even though it shouldn’t be there. And we will possibly get a bad ruling, and then we’ll get another bad ruling. And then we’ll end up in the Supreme Court, and hopefully, we’ll get a fair shake, and we’ll win in the Supreme Court, just like the [travel] ban."

How often do presidents declare such emergencies?

It is not unusual for a president to declare a national emergency. All presidents in the last 40 years have declared a national emergency though most of them have been used to level sanctions against another country, according to The New York Times. Only once before has an emergency declareation been used to mobilize the military, and that was in 2001 when then-President George W. Bush did it in response to the Sept. 11 attacks.

So how are Americans reacting to all this?

More than 60 percent of Americans disapprove of Trump’s national emergency declaration to build the border wall and 57 percent said it’s a misuse of his authority, according to an NPR-PBS NewsHour-Marist poll. Thirty-nine percent said it is appropriate. The ultimate judges could be the Supreme Court, of course, and the ultimate poll could come on Election Day 2020.