Differential etiology is a high-fallutin’ term given to a simple disjunctive syllogism in which all disjuncts in the premise but one are eliminated. The syllogism would be a persuasive argument for the one remaining disjunct but only if all the other premises are effectively eliminated. Otherwise, we are left with competing disjunctive premises that remain, without any way of embracing the “one,” for which someone is contending.
Over 100 years ago, the United States Supreme Court recognized the need for eliminating all but the claimed cause in a simple FELA negligence action. In a unanimous decision, the Court declared:
“And where the testimony leaves the matter uncertain and shows that any one of half a dozen things may have brought about the injury, for some of which the employer is responsible and for some of which he is not, it is not for the jury to guess between these half a dozen causes and find that the negligence of the employer was the real cause, when there is no satisfactory foundation in the testimony for that conclusion. If the employe is unable to adduce sufficient evidence to show negligence on the part of the employer, it is only one of the many cases in which the plaintiff fails in his testimony, and no mere sympathy for the unfortunate victim of an accident justifies any departure from settled rules of proof resting upon all plaintiffs.”
Patton v. Texas & Pacific RR, 179 U.S. 658, 663-64 (1901).
Recently the United States Court of Appeals, for the Ninth Circuit, recognized the need to rule out alternative factual explanations before a court could enter judgment on a claim of copyright infringement.1 Cobbler Nevada, LLC v Thomas Gonzales, No. 17-35041 (9th Cir., Aug. 27, 2018). The facts of Cobbler Nevada are illustrative.
Someone with access to an IP address registered to Thomas Gonzales used BitTorrent to download a copy of “The Cobbler,” an Adam Sandler movie. Cobbler Nevada LLC sued Mr. Gonzales, not for bad taste, but for infringing on its copyright to the movie. Mr. Gonzales, however, was the owner of an adult foster home, in which several other people had access to Gonzales’ IP address. Cobbler Nevada had no evidence that eliminated the possibility of downloading by other people in the home.
An amended complaint accused Mr. Gonzales of directly infringing the copyright, and alternatively, of contributing to the infringement by not policing this own internet connection.
The panel affirmed the rejection of the infringement claim because the claimant had failed to rule out downloading by someone who other Gonzales:
“The direct infringement claim fails because Gonzales’ status as the registered subscriber of an infringing IP address, standing alone, does not create a reasonable inference that he is also the infringer… .”
Id. The panel reasoned that others in the household could have accessed Gonzales’ internet connection, and that the law did not impose a duty to secure the connection from a “frugal” neighbor.
In personal injury cases, the Ninth Circuit takes a very different, and thoroughly illogical approach from its astute reasoning in Cobbler Nevada. In one Ninth Circuit case, the plaintiff claimed without much of any supporting evidence that he had sustained a drug-induced disease, when over 70 percent of cases of that disease were idiopathic. The trial court accurately diagnosed the situation as an impossible proof problem for the plaintiff because the differential etiology method could not eliminate idiopathic causes in the case before the court. Rule 702 led to the exclusion of plantiffs’ proffered opinions, and the trial court entered summary judgment for the defendants. The Ninth Circuit reversed in an ipse dixit judgment that threw logic to the wind. Wendell v. Johnson & Johnson, No. 09-cv-04124, 2014 WL 2943572, at *5 (N.D. Cal. June 30, 2014), rev’d sub nom. Wendell v. GlaxoSmithKline LLC, 858 F.3d 1227 (9th Cir. 2017).2
The two cases, Wendell and Cobbler Nevada, cannot be reconciled. The aberrant and costive reasoning of Wendell will give rise to unflattering speculation about the Circuit’s motivation. Perhaps the next edition of the Reference Manual on Scientific Evidence should have a chapter on elementary logic, to help avoid such embarrassing situations.
1 Jason Tashea, “9th Circuit rules that sharing IP address is insufficient for copyright infringement,” Am. Bar. Ass’n J. (Sept. 4, 2018).
2 For a lively vivisection of the Ninth Circuit’s decision in Wendell, see David L. Faigman & Jennifer Mnookin, “The Curious Case of Wendell v. GlaxoSmithKline LLC,” 48 Seton Hall L. Rev. 607 (2018).
