On November 26, 2012, the California Supreme Court, in Sargon Enterprises, Inc. v. University of Southern California, established a trial court's responsibility to act as a "gatekeeper" of expert witness opinion testimony on the issue of future economic damages. This decision represents a major change in California law as it relates to expert witness testimony on future economic damages and will impact the way trial judges analyze expert witness opinion testimony in medical malpractice cases, particularly in cases where plaintiffs seek substantial damages for future medical care, so-called "life care" and income replacement. It may also affect how trial judges analyze expert witness opinion testimony on issues of causation and standard of care.

In this case, the plaintiff, a dental implant company, entered into a contract with the University of Southern California (USC) to conduct a five-year clinical study of a patented dental implant. Following initial success of the clinical trial, USC failed to provide proper reports on the trials under the contract. Sargon sued USC for breach of contract. The trial court twice excluded Sargon's economic expert's testimony on future economic damages and Sargon's potential success and loss of profit based on the grounds that his testimony was too speculative. Sargon appealed the rulings and the Court of Appeal held that in both instances, the trial court erred by excluding the expert testimony. USC then appealed to the California Supreme Court.

The California Medical Association (CMA) filed an amicus brief with the California Supreme Court, arguing that the trial court thoroughly analyzed the expert opinion as required by the Evidence Code and determined that the expert opinion would not assist the jury in its fact-finding function. The brief focused on the evidentiary issues as they relate to expert witness opinion testimony offered to project future economic damages and to prove causation.

The California Supreme Court agreed with CMA and held that the trial court's "gatekeeper" function includes the duty to exclude speculative expert testimony on future economic damages. The court found that the trial court properly reviewed whether there was a reasoned basis to the expert's opinion and excluded the expert testimony after determining that the expert's methodology was too speculative.