The question of who operates Southern rail train doors is pivotal in the dispute that has led to waves of industrial action and blighted the network for much of the year.
Southern wants to take the responsibility of opening and closing carriage doors away from train guards, handing it to the the driver instead. The logic is this will free up guards to take a more customer-facing role.
Does your driver operate the doors? Perhaps not for much longer...
Both the drivers union, Aslef, and guards union, the Rail, Maritime and Transport (RMT), believe the change in policy threatens passenger safety and could lead to future job cuts – both are claims Southern rail's owner Govia refutes.
Many beleaguered passengers have questioned why there is such an issue for moving to driver-operated doors, especially when trains running on Govia's other networks – such as Southeastern and Thameslink – already have such a policy in place.
Govia tried to block the Aslef industrial action at the start of December, going to the High Court to get an injunction. And in details of the injunction process released today, Aslef revealed its wishes for a full-scale operational rollback
"The union has set its face against this extension and indeed seeks to reverse the practice on the routes where it is already established. It also wishes to establish the right to veto any new introduction of technology," the court decision outlined.
Gatwick Airport: What about London's commuters?
Also revealed in the court ruling were the bases for Govia challenging the Aslef industrial action.
One of the main ones was Govia's contention that the industrial action would have a devastating impact on passengers travelling to Gatwick Airport.
Around 50 per cent of Gatwick Express services were cancelled as a result of the strike action and 37 per cent of those travelling to Gatwick Airport used the railways, 90 per cent of these use Govia services.
"The company submits that it is inevitable that passengers will miss their flights or give up the unequal struggle and choose not to travel."
"Circumstances of the present case were highly exceptional because of the significance of Gatwick Airport"
Govia added it had estimated the strikes would cost the company £20m in addition to "serious reputational damage".