Optimal Penalties in Contracts

Contract law's liquidated damage rules prevent enforcement of contractual damage measures that require the promisor, if it breaches, to transfer to the promisee a sum that exceeds the net gain the promisee expected to make from performance; but these rules permit the promisor to transfer less than the promisee's expectation. We define a contractual damage multiplier as any number between zero and infinity by which the promisee's expected gain -- its expectation interest -- is multiplied. Multipliers of one or less thus comply with the liquidated damage rules while multipliers that exceed one do not; the high multipliers are unenforceable penalties. This paper shows that multipliers of any size can be efficient or inefficient, depending on the parties' purposes in creating them. For example, a multiplier that exceeds one will decrease welfare if used by a seller with market power to deter entry; but will increase welfare if used by parties to induce efficient relation specific investment. As a consequence, a court should inquire, not into the size of the multiplier, but into the purpose the multiplier serves for the parties.