Pennsylvania Rule of Evidence 402 and 403 relate to pretrial experiments. In these cases, a party seeks to admit tests or experiments for the purpose of showing how a particular event did or did not occur. They must first demonstrate a substantial similarity of circumstances and conditions between the test and the event in question. In a Chester County DUI, you must be prepared for a pretrial experiment relating to accident reconstruction, alcohol testing, and field sobriety reenactments. Each of these must be reviewed by your Chester County DUI lawyer to make sure that they are proper and, if not, should be objected to.
hat standard arises from Commonwealth v. Sero from 1978 and, Commonwealth v. Smith from 2002. There are whole host of problems relating to experiments and there is a significant danger of misleading the jury who may attach some sense of exaggeration or significance to the test results. Please note, however, that near-perfect identity between the experimental and actual conditions is neither attainable in reality nor is it required by law.
But the conditions of the experiment and of the actual occurrence must be sufficiently similar to provide a fair comparison. This similarity must be established and if established, any differences if any between the experiment and the actual event only go to the weight to be given to the experimental evidence. The court should weigh the probative value of the experimental evidence. The court, therefore, must weigh the value of the experiment against the dangers of confusing the issues before the jury based on unfair prejudice and undue consumption of trial time (meaning -- it is a waste of time). The courts have found probative value in the following circumstances: demonstration showing effect on nails of a wooden board breaking down word, test crash films, chemical testing of liquor, and dynamic experiments on the same year and model car. The courts of Pennsylvania have cautioned that a video tape reenactment has the potential to make a stronger impact than world testimony, any trial judge should view the tape in private prior to showing it to the jury it, especially where the opposing party claims the tape is overly prejudicial.