(CBSDC) — We now know why it appears that Supreme Court Justice Ruth Bader Ginsburg appeared to fall asleep during President Barack Obama’s State of the Union address last month – she was drinking beforehand.

In a lighthearted moment before an audience at George Washington University in Washington, D.C., Thursday night, the 81-year-old Ginsburg cracked up telling the story that she “wasn’t 100 percent sober” before going to the State of the Union.

“The audience – for the most part – is awake because they’re bobbing up and down all the time and we sit there stone-faced, sober judges,” Ginsburg said. “At least I wasn’t 100 percent sober because before we went to the State of the Union we had dinner.”

Ginsburg said that Justice Anthony Kennedy was the culprit, bringing wine to dinner.

“Justice Kennedy brought in … it was an Opus something or other, very fine California wine that Justice Kennedy brought and I vowed this year just sparkling water, stay away from the wine,” Ginsburg told the audience. “But in the end, the dinner was so delicious, it needed wine to accompany it.”

She continued: “So I got a call when I came home from one of my granddaughters and she said, ‘Bubbe, you were sleeping at the State of the Union.”