The 36th argument Irv Gornstein made before the Supreme Court was his last one, and he knew it.

It was in 2007, as an assistant to the U.S. solicitor general, and he was on the winning side in the case, Watson v. Philip Morris. “I still had it in me to do well,” he recalls. “And before then, it had been one of the great thrills of my life.”

But that day, he decided, “I had done it enough. The amount of thrill I was getting had dissipated over time.”

Gornstein decided instead that he got the biggest thrill out of helping other lawyers prepare for arguing before the Supreme Court. “I get more reward out of that than anything else in the law.”

After three years in a second-chair position at O’Melveny & Myers, working with partners Sri Srinivasan and Jonathan Hacker, Gornstein last week started a new job as the ultimate helper to Supreme Court advocates.

He is the new executive director of the Supreme Court Institute at Georgetown University Law Center, which stages moot court practices for advocates in well over 90 percent of the cases argued before the high court. Gornstein replaces Pamela Harris, another former O’Melveny lawyer who left for a top post in the Justice Department’s Office of Legal Policy.

What Gornstein describes as “the first order of business” in his new position is maintaining the high-caliber moot courts, assembling and preparing the “judges” from private practice, academia and government service who listen to practice runs and ask tough questions of advocates who range from nervous rookies to nervous veterans.

“Irv Gornstein is one of the best lawyers in the country,” said O’Melveny colleague Walter Dellinger, the former acting solicitor general. “His greatest strength is in helping people prepare for arguments.” Dellinger added that Gornstein has “an uncanny ability to crystallize arguments and to anticipate where the questioning will go.”

Georgetown law professor Richard Lazarus, a faculty director of the institute, said hiring Gornstein is “the silver lining on Pam’s departure. Irv has years of Supreme Court experience in both the SG’s office and private sector and is widely considered one of the best in providing advice to those presenting oral argument before the Court.” Lazarus said that veteran advocates who have been through several moots at Georgetown often request Gornstein as a judge. “They know his reputation.” Lazarus, an environmental law expert, is currently on leave to presidential commission on the BP oil spill.

Gornstein, 59, says he will make a high priority of involving Georgetown students in the moot courts. “Every student will be an observer in at least one of the moot courts,” he said. “It’s one of the most amazing learning experiences you can imagine.” Not only do students learn about substantive areas of the law, but they also gain insight into courtroom strategy and the importance of preparing –and preparing some more – for the barrage of questions they can expect from the justices and the moot court judges.

As excited as he is about the new position, Gornstein said, “It was wrenching for me to leave behind the people I got to know at O’Melveny.” He described Srinivasan as “one of the top two or three advocates in the country,” and Hacker as “one of the most gifted, underestimated lawyers in the country.”

But Gornstein won’t regret leaving behind his own career at the Supreme Court lectern. “My own role at O’Melveny was to be as helpful as I could to others as they prepared for argument. My role was not to argue myself. Nobody believes that, but that was the choice I made.”

Tony Mauro can be contacted at tmauro@alm.com.