What is implied in every contract?

A duty to perform is implied as a condition of the other party's performance.

under what body of law is substantial performance possible?

Common law. Not UCC because of the perfect tender rule.

What is the doctrine of substantial performance?

In non-UCC contracts complete performance MAY be excused if the breaching party's performance was substantial.

When is performance substantial?

Minor breach with respect to the overall contract = substantially performed

Material breach = not substantially performed

What wrongful acts will prevent substantial performance from being a defense?

If the breach was willful, intentional, or negligent.

When is a contract divisible?

The contract can be divided into multiple and distinct parts for which a calculation of payment can be made.