But if Chief Justice Roberts’s two seizures were so far apart, is another really likely, or likely to occur soon enough to warrant taking a drug every day? Neurologists differ.

“I would recommend taking medication,” Dr. Barkley said. “The intervals tend to get shorter and shorter, and people tend to have recurrent seizures.”

Image Chief Justice John G. Roberts Jr. leaving Penobscot Bay Medical Center on Tuesday in Rockport, Me. Credit... Robert F. Bukaty/Associated Press

He explained: “The brain learns from practice. The more you practice, the better you get, whether you’re playing the piano or having seizures. The more you have, the more you’re going to have. Most neurologists feel that the best way to intervene is to get the seizures under control as quickly as possible.”

Dr. Robert S. Fisher, director of the epilepsy center at Stanford University and a past president of the American Epilepsy Society, said: “In my view, it would be reasonable not to treat. It sounds like he went 14 years between seizures, and that’s a lot of pills to take to prevent the next seizure 14 years from now. The new ones are better than the old ones in terms of side effects, but they all have potential side effects and risks.”

Doctors say a complete medical workup is needed to find out if the two reported seizures were really the only ones that have occurred, because people with epilepsy can have mild seizures that they are not aware of. Neurologists often ask family members whether patients have certain symptoms, like daydreaming or blanking out for brief intervals, and not snapping out of it when others try to speak to them. Other symptoms may include dizziness, sensations in the stomach, feelings of déjà vu or noticing odd smells or tastes in the mouth — experiences that the patient may not recognize as seizures.

Often, Dr. Barkley said, a patient will report having had one seizure, but when asked about these other symptoms will say, “Oh, yes, that happens all the time.”