Legal Definitions - expert testimony

Expert testimony refers to specialized information or opinions presented in court by an individual who possesses unique knowledge, skills, experience, training, or education in a particular field. This testimony is offered to help a judge or jury understand complex evidence or determine a crucial fact in a legal dispute. The subject matter is typically technical, scientific, or highly specialized, falling outside the common understanding of the average person.

Here are some examples of how expert testimony is used:

• Imagine a case where a newly constructed commercial building experiences a partial collapse, leading to significant damage and injuries. A plaintiff might sue the construction company for negligence. To prove their case, they would likely call a structural engineer as an expert witness. The engineer would provide expert testimony explaining the building's design specifications, the types of materials used, and how specific construction defects or material fatigue could have led to the structural failure. This testimony helps the jury understand complex engineering principles and determine if negligence in design or construction caused the collapse.

• Consider a lawsuit involving a business accused of financial fraud, where investors claim the company intentionally misrepresented its earnings. A forensic accountant might be called to provide expert testimony. This accountant would analyze the company's financial records, balance sheets, and income statements, then explain to the court how specific accounting practices deviated from standard procedures, potentially indicating intentional manipulation of financial data. This testimony clarifies intricate financial concepts and helps the court understand the alleged fraudulent activities.

• In a criminal trial where a defendant is accused of hacking into a government database and stealing classified information, a cybersecurity specialist could provide expert testimony. This specialist would analyze server logs, network traffic, and digital footprints to explain when and how the database was accessed, what specific files were downloaded, and whether any security protocols were bypassed. This helps the court understand the technical aspects of the cyberattack and the digital evidence, which are often beyond the knowledge of non-experts.