Trump could use a national emergency - Vox.com

1. What are the two potential outcomes regarding the border wall that Trump implied in his speech?
"the government will either shut down again or “I will use the powers afforded to me under the laws and the Constitution of the United States to address this emergency.”"
2. What would Democrats argue if Trump declared a national emergency to slow illegal immigration?
Many Democrats and some legal scholars have said that Trump can’t declare a national emergency to get the border wall funded. 
3. How did Bush and Obama use the emergency powers of the president? Many presidents have declared national emergencies, including George W. Bush after 9/11 and Barack Obama during the swine flu outbreak in 2009.
4. What restrictions does the National Emergencies Act of 1976 put on the president?  the National Emergencies Act of 1976, which lets presidents issue an emergency declaration but under certain constraints — namely, Trump can only use specific powers Congress has already codified by law, and he has to say which powers he’s using. The 1976 law was actually passed to rein in presidential power and codify how presidents were going about declaring emergencies
5. If Trump does declare a national emergency, what obstacles may he face? identifying the laws and statutes he could actually use
6. How could the president use the military to accomplish this policy goal? reallocate military spending on construction projects for the wall. One law allows the defense secretary, after a national emergency declaration, to direct the army’s civil works program to construct a structure needed for national defense and use the military budget to do it.
7. What did the Supreme Court rule in Youngstown Sheet & Tube V Sawyer?  the Supreme Court ruled that President Harry Truman’s attempt to nationalize US steel mills during a strike in the Korean War was unconstitutional. 
8. How can Congress stop the president if he does declare an emergency? the National Emergencies Act was amended to require the joint resolution to override the president’s declaration — like a typical law, it requires a simple majority in the House and Senate and the president’s signature.