Donald Trump speaks before signing the executive action in the Oval Office. Credit:AP The visa-issuance process plays a crucial role in detecting individuals with terrorist ties and stopping them from entering the United States. Perhaps in no instance was that more apparent than the terrorist attacks of September 11, 2001, when State Department policy prevented consular officers from properly scrutinising the visa applications of several of the 19 foreign nationals who went on to murder nearly 3000 Americans. Most of the 19 hijackers on the planes that crashed into the World Trade Centre, the Pentagon and a field in Shanksville, Pennsylvania, were from Saudi Arabia. The rest were from the United Arab Emirates, Egypt and Lebanon. None of those countries are on Trump's visa ban list. America's founders were pro-immigration In order to protect Americans, the United States must ensure that those admitted to this country do not bear hostile attitudes toward it and its founding principles.

Donald Trump in the Oval Office of the White House in Washington, DC. Credit:Bloomberg The nation's founding principles, as reflected in the Declaration of Independence, included dissatisfaction with what were said to be overly restrictive immigration practices. It defines what non-US citizens should believe Protesters are surrounded by police at John F. Kennedy airport in New York. Credit:AP The United States cannot, and should not, admit those who do not support the Constitution, or those who would place violent ideologies over American law.

"There is no statutory requirement that non-citizens entering the United States support the constitution," said Peter Spiro, a law professor at Temple University. "The executive order seems to suggest that even temporary visitors like tourists and students should support the US constitution, which doesn't make a lot of sense." Does Trump have the power to do this? To temporarily reduce investigative burdens on relevant agencies during the review period described in subsection (a) of this section, to ensure the proper review and maximum utilisation of available resources for the screening of foreign nationals, and to ensure that adequate standards are established to prevent infiltration by foreign terrorists or criminals, pursuant to section 212(f) of the INA, 8 U.S.C. 1182(f) ... This provision is the key to the power Trump claims. It says: "Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or non-immigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate." The provision "gives the President capacious authority to deny entry to any alien or class of aliens", Spiro said. "No court has ever reversed a presidential order under it."

But he added: "In terms of the number of prospective immigrants involved, this is by far the most significant use of the power by any president." Some critics say the order runs afoul of a later law, the 1965 Immigration and Nationality Act, that bars discrimination "in the issuance of an immigrant visa because of the person's race, sex, nationality, place of birth or place of residence". The tension between the two laws has not been definitively resolved by the courts. Jennifer Chacon, a law professor at the University of California, Irvine, said a challenge to the executive order based on the later law's equal-protection principles was the most promising line of attack. In an opinion article in The New York Times, David Bier, an immigration policy analyst at the Cato Institute, a libertarian group, said Trump had at least violated the spirit of the later law. "Even if courts do find wiggle room here, discretion can be taken too far," Bier wrote. "If Mr Trump can legally ban an entire region of the world, he would render Congress' vision of unbiased legal immigration a dead letter."

It targets seven countries ... I hereby proclaim that the immigrant and non-immigrant entry into the United States of aliens from countries referred to in section 217(a)(12) of the INA, 8 U.S.C. 1187(a)(12), would be detrimental to the interests of the United States, and I hereby suspend entry into the United States, as immigrants and non-immigrants, of such persons for 90 days from the date of this order ... The countries are Iraq, Syria, Iran, Sudan, Libya, Somalia and Yemen. Some people are exempt ... (excluding those foreign nationals travelling on diplomatic visas, North Atlantic Treaty Organisation visas, C-2 visas for travel to the United Nations, and G-1, G-2, G-3, and G-4 visas).

These exceptions are mostly for diplomats, people travelling to the United Nations in New York and others involved in international organisations. The order has room to grow The Secretary of Homeland Security, in consultation with the Secretary of State, shall submit to the President a list of countries recommended for inclusion on a Presidential proclamation that would prohibit the entry of foreign nationals. The initial list may soon change and expand. But it also extends beyond the seven countries

The Secretary of State shall suspend the US Refugee Admissions Program (USRAP) for 120 days. This provision suspends all admissions of refugees, not limited to the seven countries. The order prioritises Christian refugees Upon the resumption of USRAP admissions, the Secretary of State, in consultation with the Secretary of Homeland Security, is further directed to make changes, to the extent permitted by law, to prioritise refugee claims made by individuals on the basis of religious-based persecution, provided that the religion of the individual is a minority religion in the individual's country of nationality. As a general matter, this will give priority to Christian refugees over Muslim ones. Although framed in a neutral way, this part of the order may raise questions of religion-based discrimination. Trump has said he means to favour Christian refugees.

That violates the First Amendment's ban on government establishment of religion, according to David Cole, legal director of the American Civil Liberties Union. "One of the critical questions with respect to the validity of executive action challenged under the Establishment Clause is its intent and effect," he wrote in a blog post. "If intended to disfavour a particular religion, it violates the Establishment Clause." Syrians are 'detrimental' to US interests, it says Pursuant to section 212(f) of the INA, 8 U.S.C. 1182(f), I hereby proclaim that the entry of nationals of Syria as refugees is detrimental to the interests of the United States and thus suspend any such entry until such time as I have determined that sufficient changes have been made to the USRAP to ensure that admission of Syrian refugees is consistent with the national interest. This effectively expands the ban on immigrants from Syria. How it restricts all refugees

(d) Pursuant to section 212(f) of the INA, 8 U.S.C. 1182(f), I hereby proclaim that the entry of more than 50,000 refugees in fiscal year 2017 would be detrimental to the interests of the United States, and thus suspend any such entry until such time as I determine that additional admissions would be in the national interest. Loading This cuts the cap on refugees in half. New York Times