Officials in the Trump administration say they have begun implementing a new policy which effectively denies asylum to most migrants at the United States' southern border.
A spokesperson for the Homeland Security agency has indicated the policy platform will be retroactive to 16 July, coinciding with the initial announcement of stricter border conditions.
The reform will ensure anyone who presents to the US-Mexico border, and has not sought protection from another nation first, will be denied asylum.
The effort is just one of a number of measures the Trump administration has taken to make the asylum process more difficult.
Migrants cross the border between the US and Mexico at the Rio Grande river, as they enter El Paso, Texas. Source: Getty Images North America
The US Supreme Court ruled the change could be implemented despite the efforts of advocates who had sued to put the brakes on the policy.
The court has not ruled on whether US President Donald Trump's reform is legal, rather green-lighting the administration's right to impose it temporarily.
Todd Schulte, president of immigrant advocacy group FWD.us, warns the vourt's decision is in stark contrast to America's core values.
"(This decision represents a) massive reversal of American leadership to protect the most vulnerable people fleeing extreme violence and persecution from around the world," he said in a statement.
