Court ruled on Wednesday that the government's plan to send asylum seekers to Rwanda was unlawful, delivering a major blow to Prime Minister Rishi Sunak's pledge to stop people arriving in small boats.
Here are details about the case and the issue:
WHY IS IMMIGRATION SUCH AN ISSUE IN BRITAIN?
Taking back control of the country's borders and ending the free movement of people was a major factor that led to the 2016 vote for Britain to leave the European Union.
Successive Conservative governments had promised to cut net migration to under 100,000 annually before dropping that pledge before an election in 2019.
While official data recording has changed, net immigration has continued to rise since Brexit, hitting a record of 606,000 in 2022, partly due to new visa routes for arrivals from Ukraine and Hong Kong.
WHAT IS BRITAIN'S RWANDA PLAN?
The Rwanda plan, struck in April 2022 by then Prime Minister Boris Johnson, is designed to deter asylum seekers from making the dangerous journey of about 20 miles (32 km) across the Channel from Europe in small boats or inflatable dinghies to England's southern beaches.
Last year, a record 45,775 people were detected arriving without permission in Britain in this way. So far this year, more than 27,000 have arrived on small boats.
Under the scheme, anyone who arrived in Britain illegally after Jan.