The American Antitrust Institute, a Washington D.C. organization, has written a letter to the United States Sentencing Commission recommending that fines for antitrust violations be increased.  The recommendation grows out of work done by Professors John Connor and Bob Lande, who have been studying whether the penalties (including fines, jail time, and civil liability) adequately deter would-be price fixers.  Their study, which looks at a significant amount of data over many years, suggests that price fixing is under-deterred, and that it therefore can be a rational business decision for firms to illegally fix prices, even in the current era of large fines, big jail sentences and private treble damages cases.  They specifically point out that while the Guidelines assume that price fixing raises prices by an average of 10% over what prices would be in a competitive market, there is evidence that this estimate is too low, and should be revised to 20%, if not higher.

http://www.antitrustinstitute.org/~antitrust/sites/default/files/USSCAAILetter.pdf