Currently, passengers must spend 11 nights in hotels after returning from red list countries, regardless of vaccination and Covid test status.
London-based firm PGMBM described the regulation as an "unlawful deprivation of liberty" which "violates fundamental human rights".
Whilst acknowledging the importance of safeguarding public health, the firm argued that "forcibly detaining" fully vaccinated people returning to the UK from red list countries is "unlawful".
On Thursday (12 August), the cost of staying in a quarantine hotel jumped from £1,750 to £2,285.
