weaken a precedent without overturning it completely. Thus a party with an interest in overturning an inefficient precedent would also have to consider the possibility that litigation could strengthen as well as weaken the precedent. This consideration greatly weakens the evolutionary pressures for efficiency. Parsons(1983)combined Priest's oint( that inefficient precedents would lead to increasing litigation) with the Landes and Posner point(that precedents that were litigated might become entrenched) to argue that here is a tendency for the common law to become"reckless"to favor rules that inefficiently lead to increased accidents. Cooter and Kornhauser(1980) present a complex evolutionary model in which there are some tendencies towards efficiency, but in which both efficient and inefficient rules will be observed at any time. This model and alternative definitions and implications of efficiency, are discussed in Kornhauser (1980). Von Wagenheim(1993) presents a model with similar results Hirshleifer(1982), building on my discussion of inefficiency when stakes in precedent are asymmetric, provided what may be one of the most useful and influential criticisms of the evolutionary models. Recall that in my original model and in some others, including Goodman(1979)and Landes and Posner(1979), evolutionary forces moved the law towards efficiency only if the party with an interest in efficiency had an ongoing interest in the form of he law. Hirshleifer generalized this point to show that the law could come to favor whichever party could most easily organize and mobilize resources for litigation of unfavorable precedents. This movement would be independent of efficiency. I used this point to argue that common law was more like statute law than many want to admit interest groups could use either common or statute law to achieve
weaken a precedent without overturning it completely. Thus a party with an interest in overturning an inefficient precedent would also have to consider the possibility that litigation could strengthen as well as weaken the precedent. This consideration greatly weakens the evolutionary pressures for efficiency. Parsons (1983) combined Priest's point (that inefficient precedents would lead to increasing litigation) with the Landes and Posner point (that precedents that were litigated might become entrenched) to argue that there is a tendency for the common law to become “reckless”—to favor rules that inefficiently lead to increased accidents. Cooter and Kornhauser (1980) present a complex evolutionary model in which there are some tendencies towards efficiency, but in which both efficient and inefficient rules will be observed at any time. This model, and alternative definitions and implications of efficiency, are discussed in Kornhauser (1980). Von Wagenheim (1993) presents a model with similar results. Hirshleifer (1982), building on my discussion of inefficiency when stakes in precedent are asymmetric, provided what may be one of the most useful and influential criticisms of the evolutionary models. Recall that in my original model and in some others, including Goodman (1979) and Landes and Posner (1979), evolutionary forces moved the law towards efficiency only if the party with an interest in efficiency had an ongoing interest in the form of he law. Hirshleifer generalized this point to show that the law could come to favor whichever party could most easily organize and mobilize resources for litigation of unfavorable precedents. This movement would be independent of efficiency. I used this point to argue that common law was more like statute law than many want to admit: interest groups could use either common or statute law to achieve 5
their goals(Rubin, 1982). I argued that the apparent efficiency of the common law was because most common law was developed at a time when organization of interest groups was expensive, and that more recently both common and statute law have been subject to interest group pressures. Crew and Twight(1990)expanded on this point and found common law less subject to rent seeking than statute law. Rowley and Brough(1987) and Barzel (2000) find that contract and property might be expected to be efficient, but not tort Martin bailey and i extended this theme in a formal model of the influence of interest groups on the law Bailey and rubin, 1994), and we have shown that plaintiffs attorneys have been responsible for the shape of modern tort law, using an evolutionary mechanism to shape the law Rubin and Bailey(1994). In Rubin, Curran and Curran (2001)we modeled an interest group deciding whether to use litigation or lobbying as a method of rent seeking: Osborne(2002)presents a similar model. Fon and Parisi(2003) provide an additional mechanism to explain expansion of tort(mainly product liability) law: since plaintiffs chose courts in which to file, judges who are in favor of expansive law will see more cases and have more influence than more conservative judges Although shaped by evolutionary forces, this law is socially quite inefficient An interesting set of hypotheses regarding legal evolution is in Roe(1996). Roe argues that the notion of evolution towards efficiency is an important determinant of lega form, but it is not the only determinant. He incorporates three subsidiary notions into an efficiency framework- the importance of initial conditions(borrowed from chaos theory ) path dependence, and evolutionary accidents. The result of these processes
their goals (Rubin, 1982). I argued that the apparent efficiency of the common law was because most common law was developed at a time when organization of interest groups was expensive, and that more recently both common and statute law have been subject to interest group pressures. Crew and Twight (1990) expanded on this point and found common law less subject to rent seeking than statute law. Rowley and Brough (1987) and Barzel (2000) find that contract and property might be expected to be efficient, but not tort. Martin Bailey and I extended this theme in a formal model of the influence of interest groups on the law (Bailey and Rubin, 1994), and we have shown that plaintiffs' attorneys have been responsible for the shape of modern tort law, using an evolutionary mechanism to shape the law Rubin and Bailey (1994). In Rubin, Curran and Curran (2001) we modeled an interest group deciding whether to use litigation or lobbying as a method of rent seeking; Osborne (2002) presents a similar model. Fon and Parisi (2003) provide an additional mechanism to explain expansion of tort (mainly product liability) law: since plaintiffs chose courts in which to file, judges who are in favor of expansive law will see more cases and have more influence than more conservative judges. Although shaped by evolutionary forces, this law is socially quite inefficient. An interesting set of hypotheses regarding legal evolution is in Roe (1996). Roe argues that the notion of evolution towards efficiency is an important determinant of legal form, but it is not the only determinant. He incorporates three subsidiary notions into an efficiency framework - the importance of initial conditions (borrowed from chaos theory), path dependence, and evolutionary accidents. The result of these processes 6
would be that laws would be well, but not perfectly, adapted. However, while these notions are interesting, as roe himself admits they do not as of yet provide refutable hypotheses. It would also be interesting to see if these propositions can be generalized to provide some implications In a recent important paper, Zywicki (2003) has added what he calls a"supply side"to the efficiency of law models. He points out that the evolutionary models discussed above are demand side " models, with litigants demanding efficient rules Following Berman(1983), Zywicki shows that during the formative period of the common law there was competition between several court systems. There was first competition between civil and ecclesiastical courts. Within the civil system, there were royal law, feudal law, manorial law, urban law and mercantile law courts, all competing for the fees and business of litigants. There were courts of the King's bench the Exchequer, and the Court of Common Pleas, and four more obscure royal courts as well All of these courts competed for business and fees; for example, church courts jurisdiction over testamentary succession could be used to increase the domain of these courts. This created an incentive for each court to provide unbiased, accurate and quick resolution of disputes. This is the supply side: judges and courts competed to supply efficient rules to get the business of disputants. Courts could also borrow remedies and ules from each other, which facilitated the evolution and spread of efficient rules and In this competition, the Law Merchant (Lex mercatoria) played a major role in commercial law, including contract law(Benson, 1989). Ultimately the common law
would be that laws would be well, but not perfectly, adapted. However, while these notions are interesting, as Roe himself admits, they do not as of yet provide refutable hypotheses. It would also be interesting to see if these propositions can be generalized to provide some implications. In a recent important paper, Zywicki (2003) has added what he calls a “supply side” to the efficiency of law models. He points out that the evolutionary models discussed above are “demand side” models, with litigants demanding efficient rules. Following Berman (1983), Zywicki shows that during the formative period of the common law there was competition between several court systems. There was first competition between civil and ecclesiastical courts. Within the civil system, there were royal law, feudal law, manorial law, urban law and mercantile law courts, all competing for the fees and business of litigants. There were courts of the King’s Bench, the Exchequer, and the Court of Common Pleas, and four more obscure royal courts as well. All of these courts competed for business and fees; for example, church courts’ jurisdiction over testamentary succession could be used to increase the domain of these courts. This created an incentive for each court to provide unbiased, accurate and quick resolution of disputes. This is the supply side: judges and courts competed to supply efficient rules to get the business of disputants. Courts could also borrow remedies and rules from each other, which facilitated the evolution and spread of efficient rules and remedies. In this competition, the Law Merchant (Lex mercatoria) played a major role in commercial law, including contract law (Benson, 1989). Ultimately the common law 7