A federal judge on Thursday temporarily blocked US President Donald Trump's executive order redefining birthright citizenship, calling it "blatantly unconstitutional". The decision came during the first hearing in a multi-state effort challenging the order. US District Judge John Coughenour repeatedly interrupted a Justice Department lawyer during arguments to ask how he could consider the order constitutional. When the attorney, Brett Shumate, said he'd like a chance to explain it in a full briefing, Coughenour told him the hearing was his chance. The temporary restraining order sought by Arizona, Illinois, Oregon and Washington was the first to get a hearing before a judge and applies nationally. The case is one of five lawsuits being brought by 22 states and a number of immigrant rights groups across the country. The suits include personal testimonies from attorney generals who are US citizens by birthright, and names pregnant women who are afraid their children won't become US citizens. Coughenour, a Ronald Reagan appointee, grilled the DOJ attorneys, saying the order "boggles the mind." "This is a blatantly unconstitutional order," Coughenour told Shumate. The judge said he's been on the bench for more than four decades, and he couldn't remember seeing another case where the action challenged so clearly violated the constitution. Shumate said he respectfully disagreed and asked the judge for an opportunity to have a full briefing on the merits of the case, rather than have a 14-day restraining order issued blocking its implementation. Immigration attorneys believe Trump may be trying to end birthright citizenship as a deterrent to combat illegal migration. "I think the theory that the Trump administration has is that if they deny certain immigrants access to birthright citizenship for their children, people won't want to come to the United States, whether on a temporary visa or coming illegally, that that will be a deterrent," says Julia Gelatt, Associate Director of the US Immigration Policy Programme at the Migrant Policy Institute. Gelatt says immigrants come to the US seeking better economic conditions and opportunities, and a better environment to raise their kids. "I'm not sure that birthright citizenship is a big factor in many people's minds when they decide to migrate," she added. Migrants making the dangerous journeys to the border risk their lives to potentially get across. Gelatt notes that the decision to embark on such a treacherous journey is one driven by wanting "freedom from political repression" and a desire to better support their family, regardless of whether or not their children are US citizens. The judge's ruling is temporary, but if it does become permanent, proves a major difficulty to Trump if he wants to instate the changes, and could take a really long time to pass. If the 47th US president persists on making the change, it would likely require a change to the US Constitution's 14th Amendment. The 14th Amendment clearly states in Section 1, "All persons born or naturalised in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside". Gelatt says the Trump administration says that people born in the United States have to be quote "subject to the jurisdiction thereof". She argues that that's the "linchpin" of their legal battle ahead. Any constitutional changes in the US are incredibly difficult to achieve. For that to happen, three quarters of all US states would have to agree, then two-thirds of both chambers of Congress – The House of Representatives and The Senate – would also have to approve the change. The Department of Justice later said in a statement that it will "vigorously defend" the president's executive order, which it said, "correctly interprets the 14th Amendment of the U.S. Constitution." "We look forward to presenting a full merits argument to the Court and to the American people, who are desperate to see our Nation's laws enforced," the department said. The US is among approximately 30 countries where birthright citizenship — the principle of jus soli or "right of the soil" — is applied. Most are in the Americas, with Canada and Mexico among them. The lawsuits argue that the 14th Amendment to the US Constitution guarantees citizenship for people born and naturalised in the US, and states have been interpreting the amendment that way for a century. Trump's order asserts that the children of non-citizens are not subject to the jurisdiction of the United States, and orders federal agencies to not recognise citizenship for children who don't have at least one parent who is a US citizen. The newly-sworn in president reacted to the news saying "obviously, we will appeal" to the decision. Trump also added that he wasn't surprised with the decision criticising who he mocked as the "certain judge in Seattle", noting that "there's no surprises with that judge". — Euronews