不法原因给付的困境与规则构建

不法原因给付不得返还的传统规则面临诸多困境：“不法即合法”、同为违法一方却额外获利、悖于规范目的。动态系统论回避问题真正解决方案，区分不当得利返还是否等同于承认合同有效，无法解释诸多例外情形，比例分担路径的实质仍是全部返还或否定返还。博弈论视角考察表明，不法原因给付的一般预防功能，主要在不法原因给付受领人尚未提出违法悖俗给付时发挥作用。罗马法中不法原因给付不得返还之规则适用于目的不达型返还之诉中，旨在阻止当事人于未来提出不法原因给付。由此所带来的启示在于，不法原因给付制度的一般预防功能应着眼于当事人尚未实施违法悖俗行为之时，在此基础上形成合理规则，在双方均已经提出给付时，应肯定各自返还请求权，在目的不达型不当得利案型中，若受领人尚未提出给付，应否定给付人的返还请求权。

The Dilemma and Rule Construction of Illegal Payment

Problems faced with the traditional rules that the illegal payment can''t be returned are as follows. The unlawful situation becomes legal. The party who acts illegally nevertheless acquires the benefit. Normative purpose will be infringed. By means of the dynamic system theory it doesn''t discover the practical solutions. Differentiating whether the restitution will result in the valid contract situation can''t explain many exceptions. The essence of proportional path is total return or no return. The game theory shows that the general preventive function should play a role in the case where the recipients haven''t act illegally or immorally. The denial of restitution in the Roman law is applied in the case of condictio ob rem which is intended to prevent the future illegal payment, thus providing us with the implication that the rule of denial of restitution should be aimed at the situation where one of the parties hasn''t performed the illegal or immoral obligation. When both parties have performed, the restitution right is supposed to be admitted. In the case of condictio ob rem if the recipient hasn''t performed, the restitution should be denied.