The Two Explosive Proof-of-Causation Doctrines Central to Asbestos Claims

28 Pages Posted: 6 Jan 2010

See all articles by Jane Stapleton

Jane Stapleton

University of Cambridge - Faculty of Law

Date Written: 2009


For decades the volume of asbestos claims has been a unique and mesmerizing phenomenon. This historic wave of civil claims would never have been possible had U.S. common law courts not adopted two radical dispensations from orthodox rules for the proof of causation, tantamount to causal fictions, that enabled asbestos plaintiffs to establish against each defendant factual causation to the plaintiffs’ entire physical condition for which the defendant would, therefore, be jointly and severally liable. Yet these proof-of-causation doctrines have gone virtually unremarked by courts and the academy. What are these radical proof-of-causation doctrines? Why were they adopted? Why have they yet to face rigorous academic analysis? Why was the Products Liability Restatement silent about them? What might we learn from this apparently profound failure of the restatement process?

This Article is divided into six Parts. Part I describes how, in asbestosis cases, U.S. courts absolve plaintiffs from the requirement of proving the portion of the total injury for which each culpable exposer was responsible, and thereby, in effect, proceed on the fiction that asbestosis is an indivisible injury attracting joint and several liability. Part II investigates the origin of this indivisibility-of-injury doctrine in Borel v. Fibreboard Paper Products Corp, while Part III argues that this special proof-of-causation doctrine could apply to any cumulative condition that the court is prepared to hold is not “reasonably capable of being divided” on the available evidence.

Part IV describes a second, far more radical doctrine concerning proof of causation that U.S. courts developed in claims for asbestos-related cancer whereby a plaintiff is allowed to establish factual causation against a defendant merely by showing that the defendant’s tort exposed the plaintiff to a significant amount of asbestos and therefore to a significant risk of contracting an asbestos-related cancer. In effect, this allows the plaintiff to proceed on the basis that each significant exposure to the risks of asbestos was causally involved in the triggering of the cancer. Functionally, this doctrine is tantamount to the fiction that asbestos-related cancer is contracted by a threshold mechanism, which in turn explains why this doctrine is accompanied by a rule of joint and several liability. Part V argues that this exposure-to-risk doctrine, which allows proof of causation of a condition by merely proving exposure to the risk of that condition, could apply whenever a plaintiff sues for an indivisible condition (such as a cancer), the mechanism of which is unknown, and the defendant’s tort made a substantial contribution to the risk of that condition being contracted. Such a rule has a truly explosive potential in the field of toxic torts beyond asbestos. Part VI investigates why these two extraordinary proof-of-causation doctrines have been neglected by the parties to asbestos claims, the academy, and the American Law Institute itself.

Keywords: asbestos, causation

Suggested Citation

Stapleton, Jane, The Two Explosive Proof-of-Causation Doctrines Central to Asbestos Claims (2009). Brooklyn Law Review, Vol. 74, No. 3, 2009, Available at SSRN:

Jane Stapleton (Contact Author)

University of Cambridge - Faculty of Law ( email )

10 West Road
Cambridge, CB3 9DZ
United Kingdom

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