Uber is to begin its appeal against the decision by Transport for London to deny the company a new operating licence in London.
The company is expected to file paperwork at Westminster Magistrates Court to oppose the ruling.
Friday is the deadline for the company to file the appeal, otherwise it will not be allowed to operate longer in the British capital.
Last month, the body refused to hand Uber a licence on grounds of public safety and security.
It has expressed a number of concerns over how it reports criminal offences, record checks, and how it uses technology to allegedly evade law enforcement officials.
More than 850,000 people signed an online petition launched by the company to call on TfL to reverse its decision.