In the world as it stands now, corporations get away with a lot of nastiness. Because they are legal entities set up specifically with the purpose of protecting their owners from legal responsibility, and with the sole goal of making a profit, they are effectively actively encouraged to break laws and exploit people when they can get away with it.
My solution:
Since the measure of a company's success is its share price, and since people should be held responsible for evils at their request, then if a corporation kills someone, then the shareholders (who are the ultimate beneficiaries of the killing) should be the ones that go to jail. If a corporation deliberately poisons a town, the shareholders should be the ones to serve any prison terms (along with employees who made the decisions).
This would have the immediate effect of making corporations start behaving better, because any misbehaviour would have the effect of destroying the company's share price. Proper corporate crimes like monopolistic behaviour could be handled as they are now, but actual felonies would result in people being responsible.