Some Requirements for a Computer-Based Legal Consultant

ions: the law initially defines llrightsll in terms 0 f concrete objects and ordinary human actions , but these rights are then treated as llobjects I1 themselves, and made subject to further human llactionsll ; by repeating this process of reification many times, a complex body of commercial law can be developed. Because of their technical complexity, the legal rules at the top levels of this conceptual hierarchy are difficult for most lawyers to comprehend, but this would be no obstacle for an artificial intelligence system. The commercial abstractions, in fact, are artificial and formal systems themselves, drained of much of the content of the ordinary world; and because of the commercial pressures for precision and uniformity, they are, by legal standards, well structured. A reasonable strategy for developing a computer-based legal consul tation system, then, would be to start here. This is the strategy we have followed in the TAXMAN project C61 [7] . The TAXMAN system operates in the field of corporate tax law, which is very near the apex of the hierarchy of commercial abstractions. The basic 11facts11 of a corporate tax case can be captured in a relatively straightforward representation: corporations issue securities, transfer property, distribute dividends, etc. Below this level there is an expanded representation of the meaning of a security interest in terms of its component rights and obligations: the owners of the shares of a common stock, for example, have certain rights to