During a lengthy personal injury trial arising from a train derailment, the defendants brought a motion to determine whether the plaintiff required leave under section 12 of the Evidence Act to call more than three 'participant experts' (treating doctors) who intended to proffer opinion evidence.
The court held that while treating doctors testifying strictly to history, treatment, diagnosis, and prognosis do not require leave, those offering broader opinion evidence must comply with Rule 53.03 and are subject to the three-expert limit.
The court emphasized its gatekeeper function and the need for proportionality, ruling that the plaintiff must seek leave to call more than one expert per medical specialty.
