SB 652 and Its Potential Implications for challenging Plaintiff’s Medical Causation Expert Testimony

In the ever-evolving landscape of California tort law, the recent signing into law of SB 652 on July 13, 2023, has been generating substantial discussion. This new law, which specifically addresses the standards for expert testimony in tort cases, has the potential to significantly alter the approach and strategies of attorneys defending torts in the Golden State.

At its core, SB 652 overturns the appellate decision in Kline v. Zimmer, Inc. (2022) 79 Cal.App.5th 123, a ruling that had previously been applauded by many legal professionals as a well-reasoned judgment.

A comprehensive review of SB 652 reveals the depth of its potential impact on expert testimony in tort cases. Under the previous law, an expert witness was authorized to testify in the form of an opinion, provided that the opinion was of assistance to the trier of fact and was based on matter with which the witness was familiar and could reasonably rely on. With SB 652 now enacted, the landscape has shifted.

The new law introduces additional requirements specifically related to expert opinions on medical causation when the expert is testifying for the party not bearing the burden of proof. While Plaintiffs’ experts have long been obligated to testify to a reasonable degree of medical probability that the Defendants' actions or product caused the injury, Defendants can now introduce a contrary expert's testimony only if the expert can affirm that an alternative cause exists to a reasonable degree of medical probability, or that the alleged cause does not meet this threshold.

This “reasonable medical probability” standard, now enshrined in law, brings significant implications for attorneys defending torts. Counsel for Defendants are now obligated to ensure their expert testimony meets this threshold, raising the bar for what is deemed admissible expert testimony. This new standard potentially limits Defendants' ability to propose alternative causes or raise doubts about the causation of Plaintiff's injuries unless such explanations meet this heightened standard.

This change can be traced back to the Kline case. In that litigation, Zimmer, Inc., accused by Plaintiff Gary Kline of manufacturing a defective artificial hip joint, was denied the opportunity to introduce expert testimony offering alternative explanations for Kline's complications due to these alternatives not meeting the standard of reasonable medical probability. Upon appeal, the ruling was reversed, permitting the introduction of such expert testimony. SB 652 effectively reinstates the original trial court's restrictions.

In conclusion, with the signing into law of SB 652, the landscape of tort defense in California has shifted, imposing stricter requirements on the admission of expert testimony. As always, staying informed and adaptable is vital in the practice of civil litigation. Attorneys representing Defendants in tort cases will need to carefully consider the implications of this new law, altering their strategies and approach as necessary to meet the demands of this higher standard for expert testimony.