Theresa May, the home secretary, illegally bypassed parliament to bring in temporary limit on non-EU workers, judges rule

Theresa May should have put immigration limits before parliament, high court judges have ruled Theresa May, the home secretary, should have put new immigration limits before parliament, two high court judges have ruled. Photograph: Anthony Devlin/PA

The high court has delivered a fresh blow to home secretary Theresa May's already troubled plans for a cap on immigration.

Two senior judges have ruled that the temporary limit imposed from 28 June on skilled migrants from outside the European Union is unlawful because ministers sidestepped proper parliamentary approval when it was introduced.

The ruling by Lord Justice Sullivan and Justice Burton at the high court in London followed legal challenges by the Joint Council for the Welfare of Immigrants (JCWI) and by the English Community Care Association.

The interim cap was brought in by the UK Border Agency, ostensibly to prevent a surge in applications by skilled migrants from outside Europe. It was intended as an interim measure while cabinet thrashed out an agreement over how flexible the permanent cap should be when it is introduced next April.

"This is a victory for democracy and the rule of law," said Habib Rahman, the chief executive of the JCWI. "It shows that the home secretary cannot simply sideline parliament and the requirements it has imposed to check her powers. It also has important implications for migrants in the UK who were affected by the imposition of an unlawful limit."

The immigration minister Damian Green has said he is disappointed with the ruling. "We will study the judgment and will appeal it, if we have grounds.

"We will do all in our power to continue to prevent a rush of applications before our more permanent measures are in place."

The temporary cap was designed to cut by 1,300 the number of skilled workers coming to Britain under tiers one and two of the points-based immigration system. It aimed for a 5% cut, bringing the total down to 18,700.

The Liberal Democrat who is the coalition business secretary, Vince Cable, publicly complained in September that the temporary cap had done "a lot of damage to British industry". The limit on skilled migrants is part of a package including deep cuts in the number of overseas students. They are designed to scale back annual net migration to Britain from the "hundreds of thousands to the tens of thousands", according to the government.

The court of appeal had already ruled in the summer that the home secretary acted unlawfully when retrospective changes were made to the former highly skilled migrant scheme without proper parliamentary approval.

In that ruling Lord Justice Sedley said ministers could not abandon a constitutional principle that had stood for four centuries as a pillar of democracy. "Parliament will expect the home secretary to lay before it any rules by which he or she proposes to manage immigration; the courts will expect such rules, like any other source of law, to be those and only those which have parliament's approval."

Home Office ministers announced their intention to introduce the temporary cap to parliament but did not detail how it would operate or the level of the limit on skilled and highly skilled migrants until it came into force. Details were then posted on the Home Office website but not presented to parliament.

The English Community Care Association, which represents thousands of care homes in the UK, has been concerned that the cap is having a severe effect on senior care recruitment in the care sector. About 30 Filipino migrant care workers were reported to have attended the hearing and to have been prevented from displaying a "Save our Senior Carers" banner in court.