The growth of American constitutional doctrine has been influenced, from the beginning, by the traditions of the Anglo-American common law. Judges make constitutional law, as they make other kinds of law, partly on the basis of factual premises. Sometimes these premises are merely assumed, but sometimes they are developed with the aid of counsel. However they may be determined, the facts on which a court's lawmaking is premised are called "legislative facts." In modern usage they are sometimes contrasted with "adjudicative facts," the facts of the particular case before the court.
Not all constitutional questions concern the validity of legislation. In the 1970s and 1980s, for example, the Supreme Court went through a period of reappraisal of the exclusionary rule, which excludes from a criminal case some types of evidence obtained in violation of the Constitution. One factual issue repeatedly raised during this reconsideration was whether the rule actually served to deter police misconduct. In considering that question, the Court was not second-guessing the judgment of a legislature. Yet the question was properly regarded as one of legislative fact; its resolution would provide one of the premises for the Court's constitutional lawmaking.
More frequently, however, the courts consider issues of legislative fact in reviewing the constitutionality of legislation. In many cases, particularly when the laws under review are acts of Congress, the legislature itself has already given consideration to the same fact questions. Congress sometimes writes its own factual findings into the text of a law, explicitly declaring the actual basis for the legislation. In such cases the courts typically defer to the congressional versions of reality. Similar legislative findings are only infrequently written into the enactments of state and local legislative bodies, but even there the practice has recently increased. It seems unlikely, however, that judges, especially federal judges, will pay the same degree of deference to those legislative findings.
The courts' treatment of issues of legislative fact is thus seen as a function of the standard of review used to test a law's validity. When a court uses the most permissive form of the rational basis standard, it asks only whether the legislature could rationally conclude that the law under review was an appropriate means for achieving a legitimate legislative objective. The brandeis brief was invented for use in just such cases, presenting evidence to show that a legislature's factual premises were not irrational. When the standard of review is heightened—for example, when the courts invoke the rhetoric of strict scrutiny—arguments addressed to questions of legislative fact can be expected to come from both the challengers and the defenders of legislation. A court's fact-finding task in such a case is apt to be more complicated; the complication is implicit in any standard of review more demanding than the "rational basis" standard, any real interest-balancing by the courts. Arguments about the proper judicial approach to the factual premises for legislation are, in fact, arguments about the proper role of the judiciary in the governmental system. (See judicial review; judicial activism and judicial restraint.)
The technique of the Brandeis brief was invented for the occasion of the Supreme Court's consideration of muller v. oregon (1908), upholding a law regulating women's working hours, and has been in fairly frequent use ever since. Increasingly, however, counsel have sought to present evidence on issues of legislative fact to trial courts. An early example was southern pacific co. v. arizona (1945), in which the Supreme Court struck down a law limiting the length of railroad trains. For five and a half months the trial judge heard evidence filling some 3,000 pages in the record; he made findings of legislative fact covering 148 printed pages. Justice hugo l. black, dissenting, complained that this procedure made the judiciary into a "super-legislature," but courts cannot escape from this kind of factual inquiry unless they adopt Justice Black's permissive views and abandon most constitutional limits on state regulation of commerce.
Nor are such trials of legislative fact limited to issues lying within the competence of people like safety engineers. When the California school finance case, serrano v. priest (1972), was remanded for trial, the court took six months of expert testimony centered on a single question: Does differential spending on education produce differences in educational quality? (The court's unsurprising answer: Yes.)
As the Serrano and Southern Pacific cases show, proving legislative facts at trial is considerably more costly than filing a Brandeis brief. It permits cross-examination, however, and sharpens the focus for evidentiary offerings. Even when appellate review seems certain, the trial court's sorting and evaluation of a complex record can aid the appellate court greatly. Expert testimony, the staple of such a trial, typically rests on the sort of opinion and hearsay about which nonexperts ordinarily would not be permitted to testify. Legislative facts, of course, are tried to the judge and not to a jury; furthermore, questions of legislative fact, by definition, touch a great many "cases" not in court that will be "decided" by the precedent made in the court's constitutional ruling. Just as a constitutional case is an especially appropriate occasion for hearing the views of an amicus curiae, the widest latitude should be allowed to the parties (and to an amicus) to present evidence broadly relevant to the lawmaking issues before the court.
Ultimately there is no assurance that counsel's efforts to educate a court about the factual setting for constitutional lawmaking will improve the lawmaking itself. Yet our courts, with the Supreme Court's encouragement, continue to invite counsel to make these efforts. One of America's traditional faiths, which judges share with the rest of us, is a belief in the value of education.
Kenneth L. Karst
Freund, Paul A. 1951 On Understanding the Supreme Court. Boston: Little, Brown.
Karst, Kenneth L. 1960 Legislative Facts in Constitutional Litigation. Supreme Court Review 1960:75–112.