Legal fee restrictions, moral hazard, and attorney profits

When attorney effort is unobservable and certain other simplifying assumptions (such as risk neutrality) hold, it is efficient for an attorney to purchase the rights to a client's legal claim. However, the American Bar Association Model Rules of Professional Conduct prohibit this arrangement. We show that this ethical restriction, which is formally equivalent to requiring a minimum fixed fee of zero, can create economic rents for attorneys, even though they continue to compete along the contingent-fee dimension. The contingent fee is not bid down to the zero-profit level, because such a fee does not induce sufficient attorney effort. We thereby provide a political economy explanation for these restrictions.