The essence of Progressivism is a contempt for the law. Since the progressive leader is always heading in the right direction, by definition his actions cannot be wrong. Little things like constitutions and statutes and precedent cannot be allowed to stand in the way of progress. The legal detritus can be dispensed with when the progressive leader desires; its only real function is to counter the attempts of the forces of reaction to obstruct the forces of progress.
As Jonah Goldberg points out, Progressivism is just the American-grown form of Fascism.