Causation in car accident cases is defined in Wisconsin civil jury instruction 1500:

You must decide whether someone’s negligence caused the accident or injury.  These questions do not ask about “the cause” but rather “a cause” because an accident or injury may have more than one cause.  Someone’s negligence caused the accident or injury if it was a substantial factor in producing the accident or injury.  An accident or injury may be caused by one person’s negligence or by the combined negligence of two or more people.

In a product liability case the court explained:

Or as said in Grinnell v. Charles Pfizer & Co., (1969), 274 Cal. App. 2d 424, 79 Cal. Rptr. 369. the burden is on the plaintiffs to prove the product defective but not beyond a reasonable doubt. The plaintiffs only have to introduce evidence, which affords a reasonable basis for the conclusion that it was more likely than not that conduct of the defendant manufacturer was a substantial factor in the injury.

Jagmin v. Simonds Abrasive Co., 61 Wis. 2d 60, 211 N.W.2d 810 (1973).

In a food poisoning case, tossed out on a failure of proof of negligence of a particular defendant, the court couched the causation in the more likely than not test:

Negligence can be proved circumstantially. The general rule, however, as stated in Prosser, Torts (hornbook series, 4th ed.), p. 211, sec. 39, is “that negligence must be proved, and never will be presumed.” Prosser explains that statement (pp. 211, 212) by saying:

“What is required is evidence, which means some form of proof; and it must be evidence from which reasonable men may conclude that, upon the whole, it is more likely that the event was caused by negligence than that it was not. As long as the conclusion is a matter of mere speculation or conjecture . . . it becomes the duty of the court to direct the jury that the burden of proof has not been sustained.”

Samson v. Riesing, 62 Wis. 2d 698, 215 N.W.2d 662 (1974).

In a medical malpractice case, the plaintiffs avoided a statute of limitations defense by submitting an expert affidavit:

The Pauls additionally submitted, in opposition to Skemp’s motion for summary judgment, an affidavit from an expert witness, who concluded, to a reasonable degree of medical certainty, that had Jennifer’s AVM “been [***9]  properly diagnosed at any time prior to May 1, 1995, it is more likely than not that [Jennifer] would not have sustained the injury and disability she ultimately experienced on May 22, 1995.”

Paul v. Skemp, 242 Wis. 2d 507, 625 N.W.2d 860 (2001).

McCormick Law Office attorneys in Milwaukee, Wisconsin.