The Problem Of Causal Underdetermination In Tort Law
Multiple Reasonable Behaviors Cases: The Problem Of Causal Underdetermination In Tort Law
The University of Toronto
ABSTRACT This article introduces a signi!cant yet largely overlooked problem in the law of torts: causal underdetermination. This problem occurs when the causal inquiry of a but-for test produces not one but two results, which are contradictory. According to the !rst, the negligent defendant is the likely cause of the plaintiff’s injury, whereas according to the second, she is not.
The article explains why causal underdetermination has escaped the radar of tort scholars and is perceived by courts as lack of causation. It demonstrates that the current practice in cases of causal underdetermination might lead to erroneous decisions, absolving negligent defendants of tort liability even when the evidence suggests that they are in fact the likely cause of the plaintiff’s injury.
This, in turn, the article asserts, may not only lead to underdeterrence among potential defendants, but also encourage manipulative litigation strategy to escape liability in retrospect. The article then proposes solutions that contend with causal underdetermination and resolve the dif!culties that the current practice entails.
To impose liability in negligence, a plaintiff is required to preponderantly prove three basic elements: the existence of harm, the defendant’s
Postdoctoral fellow, University of Toronto Faculty of Law. A !rst draft of this article was writ- ten during my postdoctoral fellowship at the Federmann Center for the Study of Rationality, Hebrew University of Jerusalem.
Earlier drafts of this article have been selected for presentation at the 27th Annual Meeting of the American Law and Economic Association, the 33rd Annual Meeting of the European Association of Law and Economics, the 2017 meeting of the Canadian Law and Economics Association, and the 2017 meeting of the Israeli Private Law Association. I would like to thank the participants in these meetings, as well as Natalie Davidson, David Enoch, Rea Golan,
Ehud Guttel, Alon Harel, Barak Medina, Omer Pelled, Omri Rachum-Twaig, Arthur Ripstein, Ohad Somech, Ernest Weinrib, Asaf Wiener, and the two Legal Theory anonymous referees for their helpful comments on earlier drafts. I wish to express a special thanks to Ariel Porat for his priceless comments and suggestions for this arti- cle at different stages of its writing. Lastly, I thank the Cegla Center for Interdisciplinary Research of the Law for their generous !nancial support.
Legal Theory, 25 (2019), 77–104. © Cambridge University Press 2019 0361-6843/19 doi:10.1017/S135232521900003X
unreasonable behavior,1 and the existence of a causal link between the defendant’s unreasonable behavior and the plaintiff’s harm.2 The latter requirement is the focus of this article. In particular, this article examines a distinct situation in which the plaintiff cannot meet this requirement due to a unique legal pattern referred to here as “causal underdetermina- tion.” In this pattern, the causal inquiry leads to an impossible conclusion, according to which the negligent defendant is, and is not, the cause of the plaintiff’s harm at the same time. As an example of the pattern of causal underdetermination, consider the following scenario:
The physician. A physician performs an abdominal surgery to remove a tumor (“procedure A”). The physician chooses to reach the tumor by making a large incision in the abdominal wall, a clearly negligent choice. Subsequently, the patient dies. There are two alternative procedures the physician could have performed: reaching the tumor by laparoscopy from a right approach (“pro- cedure A1”), or reaching it by laparoscopy from a left approach (“procedure A2”); both alternative procedures are considered much safer (and less costly) than the procedure that was actually performed by the physician.
Exposing the patient to unreasonable risk by performing procedure A instead of either procedure A1 or A2, the physician in the above example is clearly negligent. However, according to prevailing tort law, the physician will be held liable for her negligence only if it can be established that it is her negligence that caused the patient’s death. Consider now the following facts added to the above example:
An autopsy can prove that had the physician in the example chosen to per- form the surgery by procedure A1, the patient would likely have died anyway,
When discussing negligent behavior, the article addresses both actions and omissions. It should be noted, however, that de!nition of omissions as causes is a matter of controversy in the literature on causation. See, e.g., David Armstrong, The Open Door: Counterfactual Versus Singularist Theories of Causation, in CAUSATION AND LAWS OF NATURE 175, 177 (Howard Sankey ed., 1999) (maintaining that “[e]very causal situation develops as it does as a result of the pres- ence of positive factors alone”); Michael Moore, For What Must We Pay?
Causation and counterfactual baselines, 40 san diego l. Rev. 1181, 1222–1227 (2003); michel s. Moore, causation and responsibility (2009), at 55, 444–451 (asserting that omission liability is not cause-based liability since negative events cannot be considered as causes). For a different view, see, e.g., h.l.a. Hart & tony honoré, causation in the law (2nd ed. 1985), at 38 (stating that in the law, omissions can be perceived as factual causes, since they are “ways of describing the world . . . A real state of affairs, not just nothing”). 2. See restatement (third) of torts: liability for physical and emotional harm (2010), at §26
(stating that conduct “is a factual cause of harm when the harm would not have occurred absent the conduct”). Under prevailing tort law, in order to impose legal liability in tort, a court must! and both factual and proximate causation.
While the former is considered to be based on questions of pure fact, hinging upon the result of the but-for test, the latter is perceived to be a matter of legal policy, such that it may limit the defendant’s responsibility for the damage caused. The focus of this article is on factual causation although, as is later explained at length, its theoretical framework associates both factual and policy considerations within the counterfactual inquiry.