A license is often required to enter and remain in many businesses (such as operating a radio or TV station or a liquor store), professions (such as medicine or law), and trades (such as driving a cab or being a dietitian). Licensing is usually justified to ensure a minimum degree of competence and to protect the public against fraud and harm in cases in which it is difficult for the public to gather independent information about the quality of the product or service, and the potential for harm is quits large. Inevitably, however, licensing becomes a method to restrict entry into the business, profession, or trade and to restrict competition. Sometimes licensing seems to serve no other function than to restrict entry and competition.