Before you can file a medical malpractice claim, you will need to obtain an affidavit from a medical professional stating that he or she believes you have a valid claim and that there has been a violation of the standard of care. The healthcare professional who provides the affidavit will need to review your medical records and then execute the affidavit before a lawsuit can be filed. The medical professional should have expertise in the field of the alleged malpractice.