Here are some quotes that IMO get to the root of the problem:
"The amount of individual citizen conduct that is now potentially subject to federal criminal control has increased in startling proportions in the last several decades, beyond any understandable interest in dealing with federal programs, truly interstate issues, or international crime."
"The sheer volume of modern law makes it impossible for an ordinary American household to stay informed. And yet, prosecutors vigorously defend the old legal maxim that "ignorance of the law is no excuse." That maxim may have been appropriate for a society that simply criminalized inherently evil conduct, such as murder, rape, and theft, but it is wholly inappropriate in a labyrinthine regulatory regime that criminalizes activities that are morally neutral."
"When an innocent person sits down in a quiet room to assess his options following a federal arrest and indictment, you soon learn that you’ll be broken financially if you choose to fight and go to trial. The pressure to plead guilty — even if you are innocent — is enormous."
The problem seems to affect not only individuals, but also corporations, with criminal liability law growing greatly in scope, severity and number. Here is a boring but informative panel discussion (video): http://www.manhattan-institute.org/html/video/06-08-09clp.ht...