USA
204 Supplying an Omitted Essential Term see also Formation
When the parties to a bargain sufficiently defined to be a contract have not agreed with respect to a term which is essential to a determination of their rights and duties, a term which is reasonable in the circumstances is supplied by the court.
Topic 1 - Performances to Be Exchanged Under an Exchange of Promises
231 Criterion for Determining When Performances Are to Be Exchanged Under an Exchange of Promises
Performances are to be exchanged under an exchange of promises if each promise is at least part of the consideration for the other and the performance of each promise is to be exchanged at least in part for the performance of the other.
232 When It Is Presumed That Performances Are to Be Exchanged Under an Exchange of Promises
Where the consideration given by each party to a contract consists in whole or in part of promises, all the performances to be rendered by each party taken collectively are treated as performances to be exchanged under an exchange of promises, unless a contrary intention is clearly manifested.
233 Performance at One Time or in Installments
1. Where performances are to be exchanged under an exchange of promises, and the whole of one party's performance can be rendered at one time, it is due at one time, unless the language or the circumstances indicate the contrary.
2. Where only a part of one party's performance is due at one time under Subsection (1), if the other party's performance can be so apportioned that there is a comparable part that can also be rendered at that time, it is due at that time, unless the language or the circumstances indicate the contrary.
234 Order of Performances
1. Where all or part of the performances to be exchanged under an exchange of promises can be rendered simultaneously, they are to that extent due simultaneously, unless the language or the circumstances indicate the contrary.
2. Except to the extent stated in Subsection (1), where the performance of only one party under such an exchange requires a period of time, his performance is due at an earlier time than that of the other party, unless the language or the circumstances indicate the contrary.
Topic 2 - Effect of Performance and Non-Performance
237 Effect on Other Party's Duties of a Failure to Render Performance see also Termination
Except as stated in § 240, it is a condition of each party's remaining duties to render performances to be exchanged under an exchange of promises that there be no uncured material failure by the other party to render any such performance due at an earlier time.
238 Effect on Other Party's Duties of a Failure to Offer Performance
Where all or part of the performances to be exchanged under an exchange of promises are due simultaneously, it is a condition of each party's duties to render such performance that the other party either render or, with manifested present ability to do so, offer performance of his part of the simultaneous exchange.
239 Effect on Other Party's Duties of a Failure Justified by Non-Occurrence Of a Condition see also Termination
1. A party's failure to render or to offer performance may, except as stated in Subsection (2), affect the other party's duties under the rules stated in §§ 237 and 238 even though failure is justified by the non-occurrence of a condition.
2. The rule stated in Subsection (1) does not apply if the other party assumed the risk that he would have to perform in spite of such a failure.
240 Part Performances as Agreed Equivalents see also Termination
If the performances to be exchanged under an exchange of promises can be apportioned into corresponding pairs of part performances so that the parts of each pair are properly regarded as agreed equivalents, a party's performance of his part of such a pair has the same effect on the other's duties to render performance of the agreed equivalent as it would have if only that pair of performances had been promised.
245 Effect of a Breach by Non-Performance As Excusing the Non-Occurrence Of a Condition see also Termination
Where a party's breach by non-performance contributes materially to the non-occurrence of a condition of one of his duties, the non-occurrence is excused.
249 When Payment Other Than by Legal Tender Is Sufficient
Where the payment or offer of payment of money is made a condition of an obligor's duty, payment or offer of payment in any manner current in the ordinary course of business satisfies the requirement unless the obligee demands payment in legal tender and gives any extension of time reasonably necessary to procure it.
272 Relief Including Restitution see also Termination Remedies
1. In any case governed by the rules stated in this Chapter, either party may have a claim for relief including restitution under the rules stated in §§ 240 and 377.
2. In any case governed by the rules stated in this Chapter, if those rules together with the rules stated in Chapter 16 will not avoid injustice, the court may grant relief on such terms as justice requires including protection of the parties' reliance interests.
[Chapter 11 - Impracticability of Performance and Frustration of Purpose]

