One question...by the time Vito made the deal to provide political cover for the drug rackets, Barzini must have already figured out a way to allow Solozzo to operate withot the Corleones because he was complicit with what would have been Vito's assassination. Moreover, by the time of the meeting the Corleones were not a very strong family. Sonny had hurt their business, effectively lost the war, and Vito was not very well. Wouldn't the judges and others have taken notice of this and started loooking for other benefactors such as Barzini himself? So why make any deal with Vito?