I am aware of the following potential downsides with appointing expert witnesses
Polarisation of issues and unwillingness to concede issues
Failure to stay within the confines of one’s expertise
Not agreeing or conceding the non-essential issues after exchange of reports
Experts are paid for their services, and instructed by one party only; some bias is inevitable and corruption a possibility
Aggressive questioning by lawyers may lead to the presentation of an inaccurate picture, misleading the court/tribunal and frustrating the expert
Expecting a judge to resolve a substantial disagreement concerning a field of expertise when the judge has no criteria by which to evaluate the opinions
Success may depend on the plausibility or self-confidence of the expert rather than the expert’s professional competence