In the case of Citizens United, it's actually a pretty straightforward case. Without a constitutional amendment, it would take a very unorthodox reading of the first amendment.

The "problem" with Citizens United is that it's a very clear case.

Corporations are amoral immortals who cannot be placed behind bars. Therefore they should never be given the rights of human beings.

They don't have the rights of human beings. Humans don't lose their rights because they are in a corporation, that is the outcome of Citizens United.

"A corporation is people" is the singular of "corporations are people". Anyone saying anything different is lying or misinformed.

Think about all the times someone who definitely knew better implied that it meant a corporation is a person and trust them less.