The Corporation as a Person

The Supreme Court recently decided that corporations had the right of free speech under the U.S. Constitution, since they are persons.  But what does it mean to say corporations are persons?  Why should they have rights?  If they have free speech, should they have the vote?  What sorts of duties do they have?  Where did the idea of a corporation as a person come from, and should it be retired?  Ken and John examine the philosophical bases of corporate personhood with shareholder activist Robert Monks, co-author of Corporate Governance.