Supreme Court Justice Samuel Alito was treated at a hospital last month after leaving early from a Federalist Society dinner in Philadelphia in his honor, several sources briefed on the event told ABC News. 

Alito, who marks 20 years on the bench this year and recently turned 76, was supposed to give the keynote address at the March 20 event but did not make remarks.

He was described by those who saw him that evening as appearing “tired” and not as engaging as usual, remaining seated as attendees came over to greet him during the dinner, according to the sources. 

Alito was seen publicly on the high court bench earlier in the day for the release of an opinion in the case Olivier v. City of Brandon, a unanimous ruling involving a protestor’s free speech rights. That afternoon, the justices held a weekly private conference to discuss cases.  

The justice returned to his Virginia home later that evening, the sources told ABC. CNN’s Joan Biskupic was first to report news of the hospital visit.  

A Supreme Court spokesperson said in a statement to ABC News that Alito “felt ill during an event in Philadelphia.”

“Out of an abundance of caution, he agreed with his security detail’s recommendation to see a physician before the three-hour drive home,” the spokesperson, Patricia McCabe, said in a statement. “After that examination and the administration of fluids for dehydration, he returned home that night, as previously planned. Justice Alito was thoroughly checked by his own physician, and he returned to work the following Monday for oral argument.”

In the two weeks since the medical episode, Alito has joined his colleagues for six days of oral arguments, appearing healthy, energetic and engaged in questioning and debate. 

Interest in Alito, the second-oldest member of the Court, has been heightened in recent weeks as speculation grows over whether he may be preparing to retire. 

He has given no indication of intent to step down, but some analysts and Alito allies believe it could be a politically opportune moment for him given President Donald Trump in the White House and Republican control of the Senate through at least the end of the year. The justice also has a forthcoming book on his jurisprudence due out in October.

This is a developing story. Please check back for updates.