This is never a problem in medical malpractice cases, because it is well understood that medical malpractice claims are predicated on expert testimony, to even bring forth a claim in the first place. But lawyers — both Plaintiffs’ lawyers and defense attorneys — typically wait too long.
How do you know whether or not you need an expert? Investigate. Early. Do you have a problem with speed, with drinking, with highway design, or with a “dangerous condition?” You will not know if you have any of these problems, without investigating your claims properly.