V THE LEGAL DEFAULT PROJECT A. The Case For Defaults B. The Cost concern 1. Default rules 63 2. Default Standards C. The Asymmetric Information Concern D Summary VI MANDATORY RULES 75 A. Parties Cannot Ban Modifications B. Parties Must Accept Substantial Performance C. Parties Cannot Agree to Penalties ⅤI. CONCLUSION 83 . INTRODUCTION Contract law has neither a complete descriptive theory, explaining what the law is, nor a complete normative theory, explaining what the law should be. These gaps are unsurprising given the traditional definition of contract as embracing all promises that the law will enforce. Even a theory of contract law that focuses only on the enforcement of bargains must still consider the entire continuum from standard form contracts between firms and consumers to commercial contracts between business firms. No descriptive theory has yet explained a law of contract that comprehends such a broad domain. Normative theories that are grounded in a single norm --such as autonomy or efficiency--also have foundered over the heterogeneity of contractual contexts to which the theory is to apply. Pluralist theories attempt to respond to the difficulty that unitary See michael Trebilcock, THE LIMITS OF FREEDOM OF CONTRACT(1993). Autonomy theories thus require elastic notions of consent in order to regulate the full scope of contracting behavior with one norm. Peter Benson, Abstract Right and the Possibility of a Nondistributive Conception of Contract: Hegel and Contemporary Contract Theory, 10 Cardozo L Rev. 1077(1989); Peter Benson, Contract in A Companion to Philosophy of Law and Legal Theory, ( Dennis Patterson ed, 1996); Peter Benson, The ldea ofa Public Basis of Justification for Contract, 33 Osgoode Hall L J. 273(1995); Randy Barnett, A Consent Theory of Contract, 86 Colum. Rev. 269(1986); Randy Barnett, The Sounds of silence: Default Rules and Contractual Consent, 78 Va. L1 See Michael Trebilcock, THE LIMITS OF FREEDOM OF CONTRACT (1993). Autonomy theories thus require elastic notions of consent in order to regulate the full scope of contracting behavior with one norm. Peter Benson, Abstract Right and the Possibility of a Nondistributive Conception of Contract: Hegel and Contemporary Contract Theory, 10 Cardozo L. Rev. 1077 (1989); Peter Benson, Contract in A Companion to Philosophy of Law and Legal Theory, (Dennis Patterson ed., 1996); Peter Benson, The Idea of a Public Basis of Justification for Contract, 33 Osgoode Hall L. J. 273 (1995); Randy Barnett, A Consent Theory of Contract, 86 Colum. Rev. 269 (1986); Randy Barnett, The Sounds of Silence: Default Rules and Contractual Consent, 78 Va. L. 2 V. THE LEGAL DEFAULT PROJECT .......................................................................................59 A. The Case For Defaults ..................................................................................................61 B. The Cost Concern......................................................................................................... 63 1. Default Rules ............................................................................................................63 2. Default Standards ....................................................................................................67 C. The Asymmetric Information Concern ........................................................................70 D. Summary ......................................................................................................................73 VI. MANDATORY RULES .........................................................................................................75 A. Parties Cannot Ban Modifications.................................................................................76 B. Parties Must Accept Substantial Performance ..............................................................79 C. Parties Cannot Agree to Penalties .................................................................................81 VII. CONCLUSION ......................................................................................................................83 I. INTRODUCTION Contract law has neither a complete descriptive theory, explaining what the law is, nor a complete normative theory, explaining what the law should be. These gaps are unsurprising given the traditional definition of contract as embracing all promises that the law will enforce. Even a theory of contract law that focuses only on the enforcement of bargains must still consider the entire continuum from standard form contracts between firms and consumers to commercial contracts between business firms. No descriptive theory has yet explained a law of contract that comprehends such a broad domain. Normative theories that are grounded in a single norm -- such as autonomy or efficiency -- also have foundered over the heterogeneity of contractual contexts to which the theory is to apply.1 Pluralist theories attempt to respond to the difficulty that unitary