Three of Europe's biggest airlines have begun a legal challenge to the British government's quarantine rules for travellers, saying they should be struck down as the rule was disproportionate and had been introduced without consultation.
The legal action is being take by British Airways, Ryanair and EasyJet.
It proceeded despite the government saying the policy would be ended for English holidaymakers to countries such as France, Spain and Italy, but not the US.
The UK government introduced a blanket rule that all travellers arriving from abroad must self-isolate for 14-days after on June 8, arguing it was a crucial step to avoid a second wave of Covid-19.
The airlines criticised the decision, saying it dealt a catastrophic blow to the industry's hopes of recovery after planes were grounded by the coronavirus pandemic.
They also said that they had not been consulted on the move, and the scientific basis of the decision had not been made public.
"The measures were more severe than the measures imposed during the height of the lockdown, they're more severe than the measures imposed on people showing symptoms of Covid-19," Tom Hickman, the lawyer representing the airlines, told London's High Court.
"The fact that they are entering the UK from a Covid-19 hotspot could provide some justification, but the mere fact that they are entering the UK cannot," he added.
In documents released ahead of the court case, government lawyers said that there was no duty to consult on the policy.
Tom Hickman said that they had hoped to delay the court case so they could get a list of which countries were to be exempted from the policy, due to be published later today, but were proceeding with the case in absence of that information.