My understanding was, she was convicted on insider trading charges, very difficult to legislate or prove offense. If she was not, pick another example. Milken? My point is, we have immensely arcane laws when we think we need them.
She was convicted on obstruction of justice and lying to investigators. Nothing about her case was difficult to prove. There was a trail of evidence including emails which she and her broker attempted to alter. On top of that the prosecution had a credible witness who placed the call to notify Stewart that the CEO of ImClone was planning to sell his shares. Stewart's only defense was that she had a standing order to sell ImClone if the stock went below $60. It didn't take long to disprove that claim. So, she had inside information and she acted on this informtion for financial gain and later lied about her reasons for selling shares. Easy case.