Non-citizens living in the US will soon have to register themselves with the federal government and carry identifying documents at all times. The change was introduced by President Donald Trump via executive order and greenlit by a federal judge on Thursday. The move — which could have far-reaching repercussions for immigrants across the country — goes into effect from Friday.

Details outlined on the US Citizenship and Immigration Services website call for all aliens to apply for registration and fingerprinting if this was not done during the visa application process. They will subsequently be issued evidence of registration by the Department of Homeland Security — which aliens over the age of 18 must carry and keep in their personal possession at all times. Registration will be mandatory for people aged 14 or older who do not have legal status. It will also apply to Canadians who are in the US for more than 30 days.

Federal laws have long required people who are not US citizens but living in the country (including those here illegally) to register with the government. However the requirement has only been enforced on rare occasions with no clear example of universal use since it was first introduced in the 1940s.

The change was first heralded by the Trump administration in February — with Kristi Noem saying she would use the Immigration and Nationality Act of 1952 to “track illegal aliens and compel them to leave the country voluntarily”. The government argues that it is simply enforcing an already existing requirement — with judge Trevor Neil McFadden agreeing in his ruling.

Who is required to register?

According to details shared on the USCIS website, all individuals who were not registered and fingerprinted as required while applying for an US visa and who have remained in the United States for 30 days or longer must apply. The Department of Homeland Security subsequently issues evidence of registration to these aliens. They are required to carry these identifying documents at all times.