WASHINGTON — In December, after more than a year of research and reflection, Edward Gero went to see an argument at the Supreme Court. He was in the final stages of preparing to portray Justice Antonin Scalia onstage, and it was time to see his subject in his element.

Mr. Gero, a seasoned actor steeped in Shakespeare, felt right at home.

“The level of listening in that room was astonishing,” he said. “The only thing analogous to that is being in a theater with a good show.”

And Justice Scalia, who dominates Supreme Court arguments with probing questions laced with sarcasm, gave a fine performance.

“He’s got a wonderful speaking voice,” Mr. Gero said. “He knows how to keep the vocal energy going to the end of the thought. He lands the idea. He uses pitch. He uses inflection.”