As I commented above, the Opsware CFO went to jail not just because of her role in the options backdating scandal, but because she lied on her personal tax returns.
In particular, what the CFO was recommending was backdating the grant date of the option, which was fairly common (if not legal) among tech companies back then. What she went to jail for was backdating the exercise date of her personal options, which is kind of trivially obviously illegal to anyone who has ever filled out their tax returns. It's like if you sold stock on Dec 20th, but pretended you really sold the stock on Dec 10th when it had a lower price so you'd pay less in capital gains taxes.
In particular, what the CFO was recommending was backdating the grant date of the option, which was fairly common (if not legal) among tech companies back then. What she went to jail for was backdating the exercise date of her personal options, which is kind of trivially obviously illegal to anyone who has ever filled out their tax returns. It's like if you sold stock on Dec 20th, but pretended you really sold the stock on Dec 10th when it had a lower price so you'd pay less in capital gains taxes.