TL: DR. When your corp leaves an alliance with a mutual wardec, you not only take the wardec, it remains mutual.
We are a wormhole corp. We do PI even with our highsec pilots. You can reset your planets from highsec. Why that works is beyond me, as you can't refresh research jobs from outside the wormhole system, but I am not complaining. The pilots come back to the wormhole every week or two to deliver goods to the POS and maybe even take some goods to and from highsec markets.
Our pure wormhole pilots simply treat every unknown ship as hostile, and quite a few of the known ships too. DScan and mild paranoia are bred into your nature and you slowly forget that local ever existed. Even those of us with highsec pilots in our accounts slip into this role very easily. War declarations are meaningless for some of us.
Our part time wormhole pilots however find war declarations somewhat more painful. Hauling pilots like to fly AFK with the knowledge that Concord will eventually come to the rescue. Mission pilots like to fit for PVE and not PVP. Wardecs mean that highsec becomes troublesome.
We don't mind being shot at, but we want there to be a cost for shooting at us, at least in highsec. We also don't like staying in stations.
Our alliance got caught up in a mutual wardec, with our alliance as the defender. To be honest, without a lot of shooting on either side. But when you are travelling 30 jumps to get home, there is a strong temptation to go AFK, and regardless you don't pay full attention for the entire trip.
After discussing it within corp and up the chain with the alliance leadership, we decided it was time we try to shake the wardec. Research said that if we break out of the alliance, we would end up as the aggressor in a brand new war. This war would last a week by default and then we could let it expire. Nothing would prevent our 'nemesis' from re-declaring war, but at least then they would be paying for the privilege of shooting us.
No organisation wants to lose members. As a corp, I don't want to lose those highsec pilots. That applies to our alliance as well. We will perform all the social graces to ease the sting, but I can't believe our alliance likes see us wanting to leave.
After one last pang of concern I break us out of the alliance. We have the acceptance of the alliance. Bless it. That wardec is not only still there, but it is still mutual. We are still the defender!
Time for plan (B).