...precedent to Cox's put option. Third, Cox argued that, under the prevention doctrine, SNAP waived any such condition precedent by refusing to issue the stock options...its promise to issue the options, and so the prevention doctrine dooms its case. Under the prevention doctrine, "if a promisor prevents or...(Am. Law Inst. 1981); Richard A. Lord, Williston on Contracts § 39:7 (4th ed.), Westlaw (database updated May 2017). For the prevention doctrine to apply, Cox need only show that SNAP materially...