STATS

Dan at Lies, Damn Lies, and Statistics has a nice post on incarceration statistics. I think that he downplays the role of the "war on crime" that has resulted in harsher penalties even as crime has fallen; some discussion of public fears of crime is probably necessary. The best discussion I've found is in a book that I have used several times in my classes but I think is still out of print: Anthony King's Running Scared, a book-length version of this article at the Atlantic Monthly. Here's a paragraph from the article:

The way in which the wars on drugs and crime were fought cannot be understood without taking into account the incessant pressure that elected officeholders felt they were under from the electorate. As one former congressman puts it, "Voters were afraid of criminals, and politicians were afraid of voters." This fear reached panic proportions in election years. Seven of the years from 1981 to 1994 were election years nationwide; seven were not. During those fourteen years Congress passed no fewer than seven major crime bills. Of those seven, six were passed in election years (usually late in the year). That is, there was only one election year in which a major crime bill was not passed, and only one non-election year in which a major crime bill was passed.

If you can find a copy of the book, read it. It's fantastic. King develops an account of the extreme electoral vulnerability of American politicians (extreme in comparative terms) and then discusses several policy areas, including the "war on crime," in which this electoral vulnerability has led to perverse outcomes.