Alan Dershowitz is arguing that:
The procedural posture of Trump’s Senate impeachment trial as it ends is this: the Democrats asked for witnesses to help prove X, and the Republicans refused, on the explicit ground, put forth by Alan Dershowitz, that even if X were proven to be true, it could not — literally could not — be a valid basis for removing a president via the impeachment and conviction process.
This was, to put it in legal jargon, essentially a motion for summary judgment — that is, a procedure by which one party moves to end a proceeding on the grounds that, even if everything the accusing party is alleging is true, there still isn’t a valid legal basis for a judgment against the accused party, so therefore there’s no need for an actual trial.
What the Republicans agreed was true was this: That Donald Trump held up hundreds of millions of dollars of already appropriated aid to another country, because he was extorting that country’s leadership into announcing a fake investigation into the supposed corruption of the son of a political opponent. That’s what the Democrats alleged Donald Trump did, and that’s what Alan Dershowitz argued could not — again, not should not but could not, constitutionally — be a valid basis for removing a president.
— President Supervillain (@PresVillain) January 31, 2020
And there isn’t a single Republican who recognizes the dangerous precedent this sets? To appeal to their naked self-interest, which is all they’ve got for a moral backbone, do they realize that they are greatly weakening the power and importance of the senate in order to strengthen the executive branch into a tyranny?