Throwing out the constitution to get a wall built will come back to haunt those who want Trump to do just that. From Ron Paul at ronpaulinstitute.com:
After Congress rejected President Trump’s request for 5.7 billion dollars for the border wall, the president declared a national emergency at the southern border. Present Trump claims this “emergency” gives him the authority to divert funds appropriated for other purposes to building the border wall.
President Trump’s emergency declaration is not just an end run around Congress. It is an end run around the Constitution. Article One of the Constitution gives Congress sole authority to allocate federal funds.
While President Trump’s order may be a particularly blatant abuse of power, it is hardly unprecedented. Most modern presidents have routinely used so-called national emergencies to expand their power, often at the expense of liberty. For example, Present Franklin Delano Roosevelt used “emergency powers” to justify internment of Japanese-Americans during World War Two.
President Trump, like other recent presidents, is relying on the 1976 National Emergencies Act for legal justification for his emergency declaration. This act gives the president broad powers to declare national emergencies for almost any reason. All the president need do is inform Congress he has declared an emergency. Once the emergency is declared, the president simply needs to renew the declaration once a year to maintain a state of emergency. Since this act passed, 59 emergency declarations have been issued, with 31 of those still in effect.