The Citizens United decision and the talk that has followed imply two different and incompatible ideas of the Constitution.
The majority in Citizens United believe that the U.S. Constitution establishes a government of limited and defined powers. They asked: “Does the Constitution give government the power to prohibit speech by corporations (and others)?” The First Amendment indicated the government did not have that power.
The critics of the Citizens United decision assume the Constitution created a government of plenary powers with limited exceptions. They recognize that free speech for individuals is one such exception. But that exception is limited to natural people, not legal constructs. If there is no exception to the plenary power of government, the critics conclude, then there is no right to speak. Congress may prohibit speech by corporations (and others).
The Citizens United decision depends on an idea of the Constitution that forces government to justify its powers to citizens. The critics of the decision assume an idea of the Constitution that forces citizens to justify their rights to the government. Absent such justifications, the government has plenary power over speech and much else.
Which concept of the Constitution do you find most appealing?