As litigation consultants and expert witnesses, we spend an inordinate amount of time poring over these project records. The surprising thing is that, in most of these cases, there is a great deal of what we might call lying. It is not at all unusual to find yourself with a memo from X to his boss stating that delivery will be delayed by at least six months and a memo from X to the client, dated the same day, providing comforting assurances that the project is on schedule. Outright lying is a direct sin of commission. Equally common are sins of omission, situations where X knows something bad and neglects to tell it to the client.
Omission is a different flavor of lie.
Lying to your contract partner is morally indefensible, generally illegal, and always gets found out in litigation. All this subterfuge comes back to eat you alive during litigation. We have spoken mostly of cases where the software builder overcommits. But it is also possible for the other party to be at fault. This happens when a software buyer imposes wishful thinking deadlines on a builder, conceals real requirements to keep the price down, and hopes to impose them on the builder as freebie changes, tries to get ambiguity into a contract to be exploited later, and so on.