I do wonder though why they had to institute new banking/accounting regulations and laws if what was done was actually so "illegal".
Tha changes in law revolved primarily around others involved in the process of corporate finance, investment and advice, and those who are between the public and the corporation. What Lay is charged with regarding his banking and loan guaranty practices have been illegal for a long time. Making false statements on loan application or execution documents is fraud. Of course, fraud is something with which those Enron buccaners are well acquainted.