What expert evidence is required in a medical negligence case?

Finally, in a medical negligence case, the court should have before it some expert evidence in order to find that a breach of the standard of care caused damages to the plaintiff. As was held in Claus v. Wolfman:[34] The court ought not to be asked to make a finding that an expert or experts (the defendants) failed to meet the standard required of them by their professional peers and that their malpractice was the cause or a significant causative factor in the plaintiff's injury, in the absence of evidence of what the standard is and without the expression of even a guarded professional opinion that the defendants' conduct may have been a causal factor.[35]