For the better part of the 20th century, and much of this one, an understanding underpinned the ephemeral “American dream” and helped the US become the superpower it is. The key components of this understanding are enshrined in the First Amendment to the US Constitution, which guarantees free speech, and the fact of the US being a “nation of immigrants”. This was symbolised by the lines from ‘The New Colossus’ inscribed on the Statue of Liberty: “Give me your tired, your poor, your huddled masses yearning to breathe free”. Last week, President Donald Trump promulgated an executive order ostensibly meant...