One day after suffering an unexplained seizure, Roberts returned to his summer vacation home on remote Hupper Island and told President Bush there was no cause for alarm.
"It was a brief conversation, but one where the chief justice reassured the president that, in fact, he was doing fine," said White House spokesman Tony Snow.
But with four of the court's nine justices over the age of 70, and with the 52-year-old Roberts' health vulnerabilities more fully exposed, judicial infirmity becomes the elephant in the room. It's the political topic that's both hard to avoid and touchy to handle.
"I think it brings into sharp relief just how precarious the balance of power is on the court right now," said Nan Aron, executive director of the liberal Alliance for Justice.
In the two years that Roberts has been chief justice, many of the most controversial rulings have been 5-4 decisions, with Justice Anthony M. Kennedy providing a swing vote between two consistent groups of four - one tilting liberal, the other conservative.
Aron said she's certain that the White House has a list of potential Supreme Court nominees, even though so far "all reports are, the justices remain energized, with absolutely no signs of fatigue among them."
Roberts' release from the Penobscot Bay Medical Center did not resolve all questions about his health and potential future treatments.
These include, for instance, whether doctors will prescribe drugs to prevent a recurrence of what a Supreme Court statement described as Roberts' "benign idiopathic seizure."
The phrase means that doctors don't know what caused Roberts to collapse on a dock. He fell during his seizure Monday, suffering what the court called "minor scrapes." He was taken by boat to an ambulance on the mainland, then transported to the hospital.
Fourteen years ago, Roberts suffered a similar seizure, which led him to give up driving for several months. He wasn't asked about it during his 2005 Senate confirmation hearing, in which he assured senators in a written statement that his health was excellent, but Snow said yesterday that White House officials knew about the earlier episode.
"It was something that people did take a look at," Snow said. "It obviously was not something that was seen as an issue of overwhelming concern."
Seizures can be caused by anything from a tumor or brain infection to low blood sugar or a metabolic imbalance. Seizures typically last two to five minutes and can leave the patient sore, fatigued, confused and sometimes incontinent, according to the Merck medical manual.
Doctors usually examine a seizure patient with tools that include CAT scans and magnetic resonance imaging. They also want to know whether there have been other episodes.
"The most important thing for him is to be honest about whether he has had other seizure episodes," said Tony Coelho, a former California congressman who chaired the Epilepsy Foundation. "You have to question the individual very aggressively about whether they have had other episodes."