Here’s what MSCD 13.761–62 has to say about willful and willfully:
As it’s usually used in contracts, the word willful, as in willful misconduct, is not only vague but also ambiguous. It means intentional,” but drafters usually don’t make it clear whether the focus is on the party’s action or on the consequences of the party’s action—it’s possible to act intentionally without intending to cause damages (see 13.453). For a case that involved this ambiguity, see Johnson & Johnson v. Guidant Corp., 525 F. Supp. 2d 336, 349–51 (S.D.N.Y. 2007).
Instead of willful or willfully, use intentional or intentionally (they’re clearer words) and specify that the party’s intent pertains to the consequences of its action (see 13.457 for an example of a provision that does that), unless given the context it makes more sense to have the party’s intent pertain to its taking that action.
Why mention this? Because the other day I had occasion to put this advice into effect in the course of redrafting a commercial template for a client. The first of the phrases below exhibits the ambiguity of willful; the second one fixes it in the manner described in MSCD.
except to the extent those Indemnifiable Losses are caused by the Vendor’s negligence or willful misconduct
except to the extent the Vendor negligently or intentionally caused those Indemnifiable Losses