Unless expressly excluded, course of dealing and usage of trade can be admitted to explain or supplement the written contract, even in the face of a merger clause. Columbia Nitrogen . Mistake, Impracticability Mutual Mistake assume the contract allocates the risk. A consciously ignorant party bears the risk of mistake. Rose of Aberlone A mutual mistake of fact as to a basic assumption on which the contract was made makes it voidable.
Courts are reluctant to reallocate risks.
In contracts in which the performance depends on the continued existence of a given person or thing, a condition is implied that the impossibility of performance arising from the perishing of the person or thing shall excuse the performance. K liability is strict liability, the parties may provide for these circumstances through force majeur clauses, etc. Make the parties allocate the risks, not the courts. Risk allocation exculpatory clauses can shift negligence risk warranty disclaimer shifts risk of defect on buyer remedy limitations shifts some risk on buyer dragnet clause may push risk of default on buyer price sets risk of actual value higher or lower high interest rates liquidated damages fix risk, make it predictable minimum rent in percentage lease rescission for mistake reallocates risk risk of present and future zoning is on buyer, instability might be on seller impracticability decides risk of supervening events. Excuse by Failure of Presupposed Conditions.