Professional Liability, or Errors & Omissions (E&O), is coverage that protects your practice against claims that a professional service you provided caused your client/patient to suffer financial harm due to your mistakes (errors) or your failure to perform a service (omissions). Defending your practice in a civil suit with certain damages awarded, E&O insurance can cover the cost, even if the legal action is groundless. For medical facilities, E&O is required by law in many areas.