Do I need proof from a medical expert before filing a malpractice case? Often, yes. A certificate of merit is a statement filed by the patient's lawyer saying they consulted with a licensed medical professional and, based on that review, there is a reasonable basis to believe medical malpractice may have happened. It is not the full expert opinion and it does not prove the case by itself. It is a screening step meant to discourage weak claims before they move deeper into court.

In practice, this document can shape whether a case gets started smoothly or runs into delay. In New York, the rule appears in CPLR 3012-a. It generally requires the attorney to certify that they reviewed the facts with at least one doctor and concluded the claim has merit, or explain why that consultation could not be obtained before filing. A court may allow later compliance in limited situations, but ignoring the requirement can create procedural problems.

For an injury claim, a certificate of merit matters because it usually signals that the case has some medical support from the start. That can affect settlement discussions, early motions, and how seriously insurers and defense lawyers evaluate the claim. In delayed diagnosis cases, New York's loss of chance doctrine may also matter if negligence reduced the patient's chance of a better outcome, and the expert review behind the certificate often helps frame that issue early.