Underwater footage of van der Burgh's start revealed him doing more than the one - some reports said he did three - dolphin kicks. He won in a world record of 48.46 seconds.
Van der Burgh acknowledged he did the extra kicks but said he was forced to because the rule was not policed properly and illegal kicking had become common.
"If you're not doing it, you're falling behind," van der Burgh told the Sydney Morning Herald. "It's not obviously - shall we say - the moral thing to do, but I'm not willing to sacrifice my personal performance and 4 years of hard work for someone that is willing to do it and get away with it."
As the fastest qualifier for the Olympic final, van der Burgh swam in Lane 4, which is lined with numerous television and still cameras that clearly documented the infraction. But the cameras are for TV use only, and the judges cannot look at the images.
Katie Taylor's biggest rival believes the Irish lightweight boxer gets much more help than she needs from referees, judges and even the highest levels of the amateur sport.
Sofya Ochigava of Russia will fight Taylor on Thursday for a gold medal in the debut of Olympic women's boxing after both veteran boxers won their semifinal bouts Wednesday.
"When you go in to box against her, you begin with minus-10 points," Ochigava said in English.
Taylor is the unofficial best pound-for-pound fighter of the women's sport after winning four straight world championships with an entertaining style. Her two bouts in London have been blowout wins backed by an arena filled with thousands of raucous, flag-waving Irish fans roaring at her every move.
Ochigava knows the Irish crowd is a major advantage for Taylor in London, but thinks Taylor has plenty of advantages already.
"It's difficult," Ochigava said. "When you go boxing against Katie Taylor, you're not boxing with her. You're boxing with all judges around the table, and it's difficult boxing against all the system, but I will try like all other girls."
The international boxing association, known as the AIBA, says its judges are completely impartial and would never favor any boxer.