Chapter 2 - §4. Demonstrative evidence

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§4. Demonstrative evidence

As a general rule, demonstrative evidence is evidence used to aid the jury's understanding of the substantive evidence by replicating it in some way. E.g., People v. Duenas (2012) 55 Cal.4th 1, 20-21 (animation offered as demonstrative evidence). See "Demonstrative evidence," ch. 1, §4.2. It can consist of any evidence used to illustrate or demonstrate a tangible thing or event, including photographs, video recordings, maps, diagrams, charts, experiments, and testing. See, e.g., People v. Steskal (2021) 11 Cal.5th 332, 363-64 (life-sized mannequin dressed in officer's bloody uniform used to illustrate pathologist's testimony); People v. Williams (1997) 16 Cal.4th 153, 214 (plastic foam head with knitting needles used to illustrate expert's testimony about trajectory of bullets fired); People v. Cummings (1993) 4 Cal.4th 1233, 1291 (mannequin and dowel rods used to illustrate expert's testimony about trajectory of bullets fired), overruled on other grounds, People v. Merritt (2017) 2 Cal.5th 819. Demonstrative evidence is distinguishable from substantive evidence because it has no independent significance in the case; it is merely used to support evidence that has already been offered. See Duenas, 55 Cal.4th at 25; see, e.g., People v. Vasquez (4th Dist.2017) 14 Cal.App.5th 1019, 1039-40 (trial court erred in permitting display of timeline detailing victim's out-of-court statements to therapist as demonstrative evidence; because timeline was offered to prove charged offenses and victim's credibility, it was inadmissible substantive evidence). See "Offered for illustrative purposes," ch. 2, §4.1.1. In certain circumstances, however, demonstrative evidence can also have independent significance as substantive evidence. See "Offered as substantive evidence," ch. 2, §4.1.2. Depending on the purpose for which the evidence is being admitted (i.e., either as demonstrative evidence or as substantive evidence), the foundational requirements will be different. The court has wide discretion in permitting demonstrative evidence to illustrate a witness's testimony. People v. Mills (2010) 48 Cal.4th 158, 207.

Authentication is required for demonstrative evidence only if it is admitted into evidence. For instance, if a recording, photograph, map, or diagram is used merely to refresh the recollection of a witness, it need not be authenticated. See, e.g., People v. Seaton (2001) 26 Cal.4th 598, 658-59 (police officer used tape and transcript to refresh his recollection of earlier interview with D).

§4.1. Foundational requirements.

1. Offered for illustrative...

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