On his inauguration as president of the United States, on Jan. 20, Donald Trump took the oath of office in accordance with the U.S. Constitution. He swore that he would to the best of his ability “preserve, protect and defend the Constitution of the United States.” A week later, on Jan. 27, he signed an executive order on immigration that was manifestly unconstitutional. It indefinitely barred Syrian refugees from entering the United States, suspended all refugee admissions for 120 days, and blocked citizens of seven Muslim-majority countries – Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen – from admission for 90 days.

US President Donald Trump takes the oath of office with his wife Melania and son Barron at his side, during his inauguration at the U.S. Capitol in Washington, U.S., January 20, 2017. REUTERS/Kevin Lamarque

After the order was signed, students, visitors and holders of green cards who were lawful U.S. residents – as well as refugees from around the world – were stopped at airports in the United States and abroad. Some were blocked from entering the country and others were sent back overseas. U.S. Customs and Border Protection instructed airlines to stop passengers from the banned countries from boarding flights and to remove any who had already done so. Airline crew members from the seven countries were also barred from the United States. American diplomats were told to stop visa interviews from those countries and to halt any pending visas. University presidents tried to reassure foreign-born faculty and students that they would not be harmed.

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In making his order, Trump showed his supporters that he would keep the promises he made to them during his campaign. But his presidential oath of office was not made only to his supporters. He promised to God to preserve, protect and defend the Constitution in the interests of all the people.

The order was made while British Prime Minister Theresa May was in flight to Ankara to meet Turkish President Recep Tayyip Erdogan and conclude an arms deal with him. A few hours earlier, she had paid tribute to Trump in the hope of securing a favorable trade deal after the UK leaves the European Union. Trump spoke of the “very special relationship” between the United States and the United Kingdom.

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It is unclear whether Trump warned his new friend May of what he was about to do. She appeared to be humiliated and flailing when she met the press in Turkey. Later she had to tell her Foreign Secretary, Boris Johnson, to protest about the effect on British passport holders and to secure an exemption for them. So much for the “very special relationship.”

Trump has awakened the light sleeper of anti-Americanism abroad, weakening alliances on which Washington depends for peace and security. He has emboldened the far right across Europe. The invitation for a state visit to the UK, made with undue haste by the prime minister on behalf of Queen Elizabeth, has aroused massive protests across Britain.

More than 1.5 million people have called for the invitation to be withdrawn. Parliamentarians are campaigning to prevent him from addressing their members. London’s Mayor, Sadiq Khan, has said that the visit should be postponed until the “cruel and shameful ban” is lifted. The visit will go ahead anyway, but under massive protest. Across Muslim-majority countries in the Middle East, Iraq and Iran there is an angry backlash and credible threats of retaliation.

It was unwise of May to rush to embroil her queen in political controversy by inviting Trump to a state visit in his first days in office. It was not smart for Trump, the renowned deal-maker, to encourage the breakup of the European Union, or to question the value of NATO, or to make enemies of Muslim-majority countries. America needs strong and loyal European allies in dealing with Russian President Vladimir Putin and his threats to Ukraine and the Baltic states. The United States needs allies, in addition to Israel, in the Middle East. Trump’s mantra is “America First,” but he is leading his nation into dangerous isolation from the rest of the world.

Before Trump rushed out the immigration order he did not appear to seek advice from the intelligence community or the Justice, Defense and State Departments. (Homeland Security Secretary John Kelly said his department knew the order was coming, but that doesn’t tell us whether they had any power to refine it.) It is not clear which government lawyers, if any, were consulted. Trump has clearly acted in disregard of the Constitution and American values and the United States’ international obligations under the United Nations convention on the status of refugees.

Trump boasts that he will eliminate Islamic State and al Qaeda from the face of the earth. However, British experience in combating Irish Republican and Islamist terrorism underscores the importance of winning cooperation from communities in whose name the extremists claim to act. By alienating Muslims across the world, Trump has made enemies of those he needs as friends. His flagrant disregard for the refugee convention’s protection of those fleeing from religious and political persecution, and his would-be preferential treatment of Christian asylum seekers, make a mockery of America’s commitment to the rule of law.

In addition, he fired acting Attorney General Sally Yates for doubting the legality of his use of his executive power. Even Republicans who approve of Trump’s policy are dismayed by the incompetent way it was rushed into effect.

Trump’s ban is under legal challenge in the federal courts. The ban is based on national and religious discrimination and is surely unconstitutional. Federal judges across the country have already ruled against him. The legal challenges could go all the way to the Supreme Court, which seems unlikely to endorse his ill-conceived handiwork, even if meanwhile Neil Gorsuch, Trump’s pick for a conservative new Justice, is confirmed.

The U.S. president has no experience in public office and will have to learn that the American Republic can be governed only with respect for the American values protected by the Constitution. The one that he promised to preserve, protect and defend.

(Lord Lester of Herne Hill QC is a Liberal Democrat member of the UK House of Lords and a barrister who practices constitutional and human rights law at Blackstone Chambers in the Temple, London. His latest book is “Five ideas to Fight For.”)

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