In a lecture late at the University of Cape Town, Archbishop Tutu launched into a searing indictment of the new rainbow nation, saying it was losing its moral bearings.
The archbishop had previously asked former deputy president Jacob Zuma to relinquish his bid for the country's top job after Mr Zuma admitted to having sex with a young HIV-positive woman.
He said South Africans were erring in their daily lives, delivering the Steve Biko Memorial Lecture.
"What has come over us? Perhaps we did not realise just how apartheid has damaged us so that we seem to have lost our sense of right and wrong," he said
"Is it not horrendous ... for an adult man to rape a nine-month-old baby?" he said, referring to a recurring problem in one of the world's most crime-ridden nations.
"We are not appalled that some of us can chuck people out of moving trains because they did not join" a strike, he said.
"What has happened to us? It seems as if we have perverted our freedom, our rights into licence, into being irresponsible,” he said.
High expectations
"Part of our own disillusionment is the high expectations that we had," Archbishop Tutu told reporters at a British High Commission function.
"We imagined that because we had this noble cause, the vast majority of people were altruistic, were idealistic, and we thought we were going to translate that and transfer it automatically to the time when we were then free. It's not happened."
Archbishop Tutu underlined that the need to break laws ended with the demise of apartheid in 1994, saying it was justified then as "we wanted to make South Africa ungovernable."
"We have achieved our goal. We are free ... We have an obligation to obey the laws made by our own legislators. We should be dignified, law abiding citizens ... proud of our freedom won at such great cost," he said.
"We should not devalue it. We should not abuse our children, our womenfolk."
Serious problems
The archbishop said South Africa had "very serious" problems such as poverty, AIDS, corruption and crime but had achieved a remarkable degree of stability in 12 years of democracy.
"Which country doesn't have problems? ... When you think of, say, America. It's been free for 300 years. What has Katrina revealed?" he asked, referring to the hurricane that flooded New
Orleans in 2005 and focused world attention on poverty in the US.
"You see some horrendous things that you would not have expected in the country that is the only superpower," Archbishop Tutu said.