Uber has lost its attempt to prevent its drivers being forced to take English language tests.
The ride-hailing app went to court in August last year after Transport for London (TfL) said that drivers should have to prove their ability to communicate in English.
Uber argued that the standard of reading and writing required by the test was too high.
The ruling will also apply to all minicab firms in London.
"TfL are entitled to require private hire drivers to demonstrate English language compliance," said Judge John Mitting as he rejected Uber's claim.
However, the judge ruled that Uber would not be required to open a UK-based call centre.