TEN DECISIONS BETWEEN 1965 AND 1974 IN WHICH DETERMINATIONS OF SOCIAL FACT WERE CRUCIAL TO THE ESTABLISHMENT OF LEGAL RULES WERE REVIEWED. BOTH COURT OPINIONS AND CASE RECORDS WERE STUDIED TO DETERMINE WHETHER SOCIAL SCIENCE THEORY OR DATA HAD BEEN RELIED UPON BY LITIGANTS. PSYCHOLOGISTS AND OTHER SOCIAL SCIENTISTS WERE EMPLOYED AS CONSULTANTS TO EVALUATE COURT DETERMINATIONS AND THE QUALITY OF ADVOCACY. IN ANALYZING THE FINDINGS, IT WAS NECESSARY TO KEEP IN MIND THE DIFFERENCES IN VIEWPOINT AND PROCEDURES BETWEEN SOCIAL SCIENCE AND LAW. AN EXAMINATION OF FULL COURT RECORDS IN THE 10 CASES INDICATED THAT THERE WAS SELDOM ANY SERIOUS EFFORT BY LAWYERS TO PRESENT EMPIRICAL DATA OR EXPERT OPINION ADDRESSING THE SOCIAL FACT ISSUE. THE QUESTION OF PRIVACY PRESENTED SPECIAL DIFFICULTIES. IT WAS DETERMINED THAT BEHAVIORAL SCIENCE MIGHT CONTRIBUTE TO MORE RATIONAL JUDICIAL DECISIONS BY DEFINING SOME OF THE CONDITIONS UNDER WHICH INTRUSIONS OF PRIVACY MIGHT BE PERMISSIBLE. THE DEFINITIONAL PROBLEM WITH THE LEGAL CONCEPT OF PRIVACY EMERGED MOST FREQUENTLY IN CASES WHERE THE LEGAL STANDARD WAS A 'REASONABLE EXPECTATION' OF PRIVACY. TWO MAJOR RECOMMENDATIONS ARE OFFERED TO DEVELOP A SOCIAL SCIENCE APPROACH TO THE LAW OF PRIVACY: (1) LAWYERS ENGAGED IN PUBLIC POLICY LITIGATION SHOULD DEVELOP CLOSER COLLABORATION WITH SOCIAL SCIENTISTS; AND (2) THE MOVEMENT TO INCLUDE SOCIAL SCIENTISTS ON LAW SCHOOL FACULTIES SHOULD BE SUPPORTED AND ACCELERATED. REFERENCES ARE INCLUDED. (DEP)