As most of us know, corporations are created through the action of the laws of the state from which the corporation files for existence. The laws of each state impose various conditions upon those corporations - things like a board of directors, meetings, accounting rules, bulk-transfer limitations, etc.
I am thinking that I ought to draft a California initiative that would add to California's corporations code various rules that would require that any and all use or expenditure of corporate assets for political purposes obtain explicit approval of 100% of the holders of all outstanding shares.
That would effectively nullify Citizens United except in those cases where the corporation could get the assent of all of the owners (shareholders) of the corporation. For small, closely held corporations this would be often be easy to do. For larger corporations this would usually be very hard (but not impossible.)
I'm thinking of things like allowing a small amount that could be spent without approval and whether there could be some mechanism to override dissenters, perhaps by requiring a buyout offer.