Strangeness in Citizens United case
I could see an argument (were this a State case) that a corporation isn't a "citizen" for privilege or immunities purposes, or a "person" for due process purposes. I could even see (altho I have problems with it) an argument that a corporation is entitled to lessened First Amendment protections. But from fn. 55 of Stevens' dissent:
In normal usage then, as now, the term “speech” referred to oral communications by individuals. See, e.g., [various citations]. Given that corporations were conceived of as artificial entities and do not have the technical capacity to “speak,” the burden of establishing that the Framers and ratifiers understood “the freedom of speech” to encompass corporate speech is, I believe, far heavier than the majority acknowledges.
But (1) this would mean that "symbolic speech," such as protests and flag-burning, have zero constitutional protection and (2) First Amendment cases involving corporations -- New York Times v. Sullivan (limits on defamation suits by public officials and figures) and NAACP v. Alabama (right of a controversial group to keep private its members names) were entirely wrong.