A cap on migrant workers imposed by the Home Secretary has been ruled illegal.
The High Court said Theresa May had unlawfully tried to "side-step parliamentary scrutiny" when she set the temporary limit of granting only 24,100 visas for non-EU workers. Lord Justice Sullivan said the changes were substantive and should have been laid before Parliament.
The Home Office said it was considering an appeal against the decision, which leaves a key plank of Government immigration policy in limbo. But it does not affect the permanent cap being introduced from April.
Within weeks of taking up her post, Mrs May announced that only 24,100 non-EU workers would be granted visas to Britain by April 2011.
But the High Court ruled that she had acted outside her powers and had not allowed her plans to be scrutinised properly by Parliament.
The cap has been denounced by the care industry, which has warned it is struggling as a result to fill staff vacancies in care homes.