The High Court in London has ruled against a temporary cap on skilled workers migrating to Britain from countries outside the European Union.
Judges say the measure was introduced unlawfully.
Home Secretary Theresa May introduced the cap of 24,100 non-EU skilled workers per month in June as an interim measure ahead of a permanent cap.
But the measure was challenged by the Joint Council for the Welfare of Immigrants and English Community Care Association.
Judges ruled on Friday that ministers had "sidestepped" Parliamentary scrutiny.
The BBC reports the ruling has nullified the current temporary cap, meaning it is no longer in force.
But ministers can introduce a new cap when Parliament returns in January. This would come into effect immediately.
As a first step, ministers introduced a temporary cap for non-EU skilled workers of 24,100 a month in June, in line with a Conservative election commitment.