What is the collateral source rule in medical malpractice cases?

Under the traditional collateral source rule, a jury, in calculating a plaintiff's damages in a tort action, does not take into consideration benefits--such as medical insurance or disability payments--which the plaintiff has received from sources other than the defendant--i.e., "collateral sources"--to cover losses resulting from the injury. (See, e.g., Helfend v. Southern Cal. Rapid Transit Dist. (1970) 2 Cal.3d 1, 84 Cal.Rptr. 173, 465 P.2d 61.) Section 3333.1 alters this rule in medical malpractice cases. ²⁰ Under section 3333.1, subdivision (a), a medical malpractice defendant is permitted to introduce evidence of such collateral source benefits received by or payable to the plaintiff; when a defendant chooses to introduce such evidence, the plaintiff may introduce evidence of the amounts he has paid--in insurance premiums, for example--to secure the benefits.

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