What criteria might be used to establish someone as an expert witness?

To establish someone as an expert witness, criteria typically include their education, training, and professional experience in the relevant field. They should possess specialized knowledge that is beyond that of an average person, and their qualifications must be demonstrable through credentials, publications, or prior work in the area. Additionally, their ability to communicate complex information clearly and effectively in court is essential. Courts often assess these factors to determine the witness's reliability and relevance to the case at hand.