The movie star was among 15 activists who were handcuffed and taken into custody for refusing requests to move on and abandon a protest outside the Sudanese embassy. He was charged with disorderly crossing a police line.
Clooney, his father Nick and the others arrested were demonstrating as part of a humanitarian campaign to raise awareness about the fragile situation between Sudan and the newly-independent South Sudan, where locals have been driven into caves in the Nuba Mountains to avoid bombing raids on their villages.
And activist Fred Kramer, who was also arrested, admits Clooney made sure the experience was not all bad.
Appearing on U.S. news show Access Hollywood Live on Monday (19Mar12), Kramer said, "We were arrested by the secret service because we were on embassy grounds and they walked us over to the paddy wagon (police van). I was in the paddy wagon with George and with, I think, three Congressmen (and) Martin Luther King III... It was a real honour to be in a paddy wagon with those people.
"George was really the movie star gentleman; he made everybody comfortable, he was cracking jokes... He tried to pass himself off as Brad Pitt."
Kramer added the time he spent behind bars with Clooney was quite enjoyable: "It was really pretty incredible. It was like a little conference. We had a table in the centre of the cell... and we spent those couple of hours... talking about what could be done, how the United States government can... lead the international community in letting that Khartoum regime know that this kind of behaviour is just no longer tolerable in the world today."
Clooney was released after two hours and immediately held an impromptu press conference, during which he joked about his arrest and urged American politicians to intervene in the Sudanese wars to avert a looming starvation crisis.