Twenty states now allow nurse practitioners to practice medicine without being affiliated with a physician, and The New York Times reported that eight more states are contemplating similar measures.

Advocates say the trend will help fill medical care gaps in locations where physicians are scarce, such as Nebraska, which is largely rural and has difficulty attracting doctors to the state. Opponents of the laws, which include the American Medical Association, argue that nurse practitioners lack sufficient knowledge to practice on their own.

The number of NPs has been rising. The American Association of Nurse Practitioners said in January that the number of NPs, which is around 205,000, had doubled over the past 10 years.