House Bill No. introduced by A. Nicastro establishes new criteria for courts to consider when allowing expert witnesses to testify under Rule 702 of the Montana Rules of Evidence. The bill mandates that the court evaluate four specific factors: whether the expert's knowledge aids in understanding the evidence or determining a fact, whether the testimony is based on sufficient facts or data, whether it stems from reliable principles and methods, and whether the expert's opinion reliably applies these principles to the case's facts.

Additionally, the bill includes a codification instruction indicating that the new section regarding expert witness testimony is intended to be integrated into Title 26, chapter 1, part 1 of Montana law. This integration ensures that the provisions of Title 26, chapter 1, part 1, will apply to the newly established criteria for expert witness testimony.