Chapter 2 - §7. Experimental evidence

• Jurisdiction: United States

§7. Experimental evidence

Experimental evidence is commonly introduced to test theories of a case—that is, to demonstrate how a particular event occurred or did not occur. See 2 Witkin, California Evidence (5th ed. 2012), Demonstrative, Experimental, and Scientific Evidence §37. Experimental evidence can be conducted inside or outside the courtroom. In permitting an experiment to be conducted in the courtroom, the court has wide discretion. People v. Skinner (1st Dist.1954) 123 Cal. App.2d 741, 751. As an alternative to an in-court demonstration, the court may permit photographs or recordings of the experiment to be introduced or simply permit a witness to testify about the experiment and its results. See id.; see, e.g., People v. Marshall (1996) 13 Cal.4th 799, 833 (photograph of reconstructed crime scene).

§7.1. Foundational requirements. To establish a proper foundation for experimental evidence, the proponent must prove that (1) the conditions of the experiment were substantially similar to the actual events, (2) the person testifying about the experiment is qualified, and (3) the evidence will not consume too much time, will not confuse the issues, and will not mislead the jury. See Evid. C. §352; People v. Jackson (2016) 1 Cal.5th 269, 342; People v. Zaragoza (2016) 1 Cal.5th 21, 50; People v. Lucas (2014) 60 Cal.4th 153, 228, disapproved on other grounds, People v. Romero (2015) 62 Cal.4th 1; People v. Jones (2011) 51 Cal.4th 346, 375; People v. Bradford (1997) 15 Cal.4th 1229, 1326.

Note When an experiment is not being offered as circumstantial evidence of an issue in the case, the experiment does not have to meet the requirement of substantial similarity. E.g., People v. Carter (1957) 48 Cal.2d 737, 750 (blood-spatter experiment did not have to meet requirement of substantial similarity because it was offered to prove expert's qualifications, not to prove issue in case); People v. Guillebeau (1st Dist.1980) 107 Cal.App.3d 531, 550-51 (experiment used to determine if wear pattern in shoe could be worn away in four-day period did not have to meet requirement of substantial similarity; experiment was used to determine characteristic of shoe pattern, not to prove how D wore down his shoes).

1. Substantially similar conditions. The conditions of the experiment must be substantially similar to the actual events being portrayed. People v. Turner (1994) 8 Cal.4th 137, 198, disapproved on other grounds, People v. Griffin (2004) 33 Cal.4th 536. But the conditions do not need to be exact or identical, especially if the similarity...