A corporation enjoys special tax and legal status not available to individuals. In exchange for that status, the government can and should demand that they give up their so-called "right" to free speech (the same way non-profit groups can be restricted so long as they wish to retain their non-profit status).
The law should also be changed to make it easier to pierce the corporate veil and prosecute executives, employees, and board members. The defense of "I didn't know what the other guys were doing so I couldn't see the whole picture" should be evidence of conspiracy, not a defense.
Punishment for corporations found guilty of crimes should be more than token fines. Yes, non-employee shareholders of publicly-traded companies enjoy limited liability for those companies' actions, but they do have liability up to the value of the stock. No, it doesn't make sense to give corporations the "death penalty" very often, so long as the company had some legal business, but the government should be better able to seize assets, primarily stock and options, especially from executives. The public will demand more accountability from the companies they own if they know that corporate crime will more often cost them their ownership directly, not just as a blip in profit.
Because government in this country is so limited and the benefits of monopoly (or, more likely duopoly) so immense, corporates naturally grow in size until they are "too big to fail". Again, as with free speech in exchange for special tax status, corporations do not have the right to grow so big or become so vital to the economy that their collapse would lead to destabilization of the country. The government should regularly be reviewing this and taking actions to break those companies up, or prevent the mergers that lead to this situation in the first place. Maximizing efficiency and profits through consolidation when times are good leads to increased instability when times are bad. It is the government's job to regulate the economy to ensure the general welfare, and that includes smoothing both the highs and lows.