In this forum we have nomerous times discussed whether a carrier is able to extend the "extraordinary circumstances" exemption to subsequent flight(s), i.e. where a flight is delayed or cancelled due to e.g. wheather related delay or diversion of incoming flight.

The Danish Supreme Court rendered a landmark decision Friday on the "knock-on" effects of a SAS flight, CPH-IAD diverting to PHL due to adverse wheather conditions at IAD. The pax were claiming compensation for the delay of the same flight the following day after SAS ferried the aircraft empty to CPH (and even transferred crew to OSL to replace the crew of the incoming aircraft from the US as the crew was unable fly all the way to CPH) but nevertheless the CPH-IAD flight the following day (sheduled to operated by the same aircraft) was delayed due to the knock-on effects of the diversion in the US the day before.

As you will be aware the arguments of pax/claims agencies have always been that the carrier needs to have aircraft and crew available even at outstations and therefore the carrier is liable to pay compensation if also the subsequent flight(s) is delayed/cancelled even if the initial flight may be delayed/cancelled due to "extraordinary circumstances".

The Supreme Court reversed the decisions of the lower courts and acquitted SAS from paying EC Reg. 261/04 compensation. The Supreme Court states that it would be an "ureasonable burden on SAS to have contingency plans/equipment available for situations like this where..." [and the Supreme Court refers the particulars of the delay in question].

Unfortunately only in Danish yet, but you will find the decision here:

http://www.hoejesteret.dk/hoejestere...nts/214-16.pdf

I'm quite sure that carriers will try to rely on this decision in matters where pax of the subsequent flights are affected by a delay or cancellation of the incoming aircraft/earlier flight due to weather, ATC etc.