Standards of Proof in Civil Litigation: An Experiment from Patent Law

TABLE OF CONTENTS I. Introduction II. Standards of Proof--An Overview A. The Burden of Proof B. The Role and Types of Standards of Proof C. Previous Empirical Studies 1. Survey Evidence 2. Experimental Studies III. Microsoft v. i4i and Presumption of Validity in Patent Law IV. Methodology and Study Design A. Hypotheses About i4i's Impact B. Why an Experiment? C. Study Design V. Discussion A. Results B. Implications C. Directions for Future Research VI. Conclusion Appendix A Appendix B I. Introduction Our litigation system is based upon assumption that standards of proof matter. (1) They serve instruct factfinder concerning degree of confidence our society thinks he should have in correctness of factual conclusions. (2) The various standards of proof reflect legal system's judgment about proper allocation of risk between litigants, as well as relative importance of issues at stake. (3) For example, in criminal cases where defendant's liberty may be at stake, prosecution carries burden of proving every element of criminal charge beyond a reasonable doubt. (4) In contrast, of a much less stringent standard, is most common in civil cases. (5) The third main standard, and convincing is an intermediate standard employed in civil litigation when the individual interests at stake ... are both 'particularly important' and 'more substantial than mere loss of money.' (6) But despite perceived importance of standards of proof, few empirical studies have tested lay jurors' understanding and application of standards of proof, particularly in civil litigation. (7) Specifically, to our knowledge, there has not been a large-scale study of a demographically representative population comparing jurors' decisions when confronted with two standards of proof used in civil litigation: (1) preponderance of evidence, and (2) clear and convincing (8) Patent law recently presented an opportunity to assess impact of varying standard of proof in civil litigation. Under Section 282 of Patent Act, every claim in a issued U.S. Patent and Trademark Office (USPTO) is presumed to be valid. (9) This same statute also provides that [t]he burden of establishing invalidity of a or any claim thereof shall rest on party asserting such invalidity. (10) However, statute fails to specify standard of proof necessary to overcome this presumption of validity. In a recent case, Microsoft Corp. v. i4i Ltd. Partnership (i4i), U.S. Supreme Court heard competing arguments regarding proper standard of proof for finding a invalid. (11) Microsoft argued that preponderance of evidence standard should apply, at least when USPTO had not considered prior art that allegedly invalidated patent. (12) But Court unanimously affirmed U.S. Court of Appeals for Federal Circuit's (Federal Circuit) longstanding interpretation that invalidity must be proven by clear and convincing evidence. (13) However, Court also held that if party challenging a patent's validity could introduce new evidence in litigation that had not previously been considered USPTO during patent's examination, then the challenger's burden to persuade jury of its invalidity defense clear and convincing evidence may be easier to sus-sustain. (14) In such situations, jury should be instructed that it has heard evidence that [US]PTO had no opportunity to evaluate before granting patent and to consider that fact when determining whether an invalidity defense has been proved clear and convincing evidence. (15) But at same time, Court declined endorse any particular formulation for such an instruction. (16) Both parties in i4i and Court apparently assumed that standard of proof would affect lay jurors' decisions regarding invalidity, at least on margins. …