Legal Definitions - demonstrative evidence

Demonstrative evidence refers to physical items, visual aids, or other devices presented in a trial or hearing to help the judge or jury understand the facts a party is trying to prove. Unlike testimonial evidence (what a witness says) or documentary evidence (written documents), demonstrative evidence is primarily used to illustrate, explain, or clarify other evidence. It makes complex information more accessible and comprehensible to those making decisions in court.

Here are some examples:

• In a medical malpractice lawsuit, a plaintiff might introduce a detailed, animated 3D model of the human spine to illustrate how a surgeon's alleged error during an operation caused a specific nerve injury. The animation would show the correct surgical procedure versus the procedure that was performed, highlighting the point of alleged negligence.

  This is demonstrative evidence because the 3D model and animation are not the actual injury or the actual surgery itself, but rather a visual tool created to help the jury understand the complex medical testimony and expert opinions about how the injury occurred.

• During a product liability case concerning a defective household appliance that caused a fire, an attorney might present a large, professionally rendered diagram of the appliance's internal wiring system. This diagram could use color-coding to show where the alleged electrical fault occurred, based on expert testimony and physical evidence of the damaged appliance.

  This diagram serves as demonstrative evidence by visually simplifying complex electrical schematics and expert analysis, making it easier for the jury to grasp the technical details of the product's design and the location of the alleged defect.

• In a dispute over property boundaries, one party might present a large, laminated aerial photograph of the disputed land, overlaid with precise survey lines and markers indicating where they believe the true property line lies. This visual aid would be used in conjunction with surveyor testimony and official property deeds.

  This aerial photograph with overlaid markings is demonstrative evidence because it visually clarifies the geographical context and the specific points of contention regarding the property line, helping the court understand the surveyor's testimony and the legal documents.