Trump had sought to rescind the Deferred Action for Childhood Arrivals (Daca) programme, which protects young people from being deported if they entered the US without documentations as children.
The BBC reports that the policy protects 650,000 people who had entered the US in this way while they were juveniles; the American Immigration Council provides a higher figure.
Most of the children and young people shielded by Daca are from Mexico and Latin American countries, the BBC adds.
The American Immigration Council explains that it has allowed “almost 800,000 eligible young adults to work lawfully, attend school, and plan their lives without the constant threat of deportation, usually to an unfamiliar country.”
The policy only provides temporary protection, though. It must be renewed every two years, and individuals can only apply if they are under the age of 31 and if they arrived in the US before their 16th birthday.
Applicants have to go through a background check and will only be approved for the protection from deportation if they meet certain criteria.
This includes a clean criminal background from a “felony or significant misdemeanour”. They must also be in school, have been honourable discharged from the military, or have recently graduated.
The Trump administration has tried to have the policy removed since September 2017, when it set in motion attempts to wind it down and prevent new applications for the protection that DACA offered.
But Trump’s action was halted in early 2018 by a federal judge in California, the American Immigration Council reports, and further scuppered by a federal judge in New York soon after.
As a result, it became possible for people to again renew their protected status under the policy for a further two years.
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He wrote: “These horrible & politically charged decisions coming out of the Supreme Court are shotgun blasts into the face of people that are proud to call themselves Republicans or Conservatives.
“We need more Justices or we will lose our 2nd. [sic] Amendment & everything else. Vote Trump 2020!”
Trump also tweeted his intention to “start this process all over again,” suggesting that his Administration would make yet another attempt to end the policy.
Meanwhile, Joe Biden, who is considered the main rival against Donald Trump in the upcoming presidential election this November, has stated that he would seek to make the programme permanent if he were elected this year, the BBC reports.
And Former president Barack Obama praised the court’s ruling, calling for a Democratic president and Congress to ensure “a system that’s truly worthy of this nation of immigrants once and for all,” the BBC adds.