The Supreme Court has allowed Texas to enforce one of the toughest immigration laws enacted by any US state in recent memory.

The measure allows police to arrest and prosecute those suspected of illegally crossing the US-Mexican border.

The Biden administration has challenged the law, calling it unconstitutional.

Crossing the US border illegally is already a federal crime, but violations are usually handled as civil cases by the immigration court system.

One reason the Texas law, SB4, is so controversial is because courts have previously ruled that only the federal government can enforce the country’s immigration laws, not individual US states.