Derp-showitz: Trump team doesn't like the Constitution, bases its defense in English law - 2020-01-24
Yesterday I spent a few paragraphs deconstructing Alan Dershowitz's argument (which he's expected to make next week on the Senate floor) that "high crimes and misdemeanors" requires "criminal-like conduct," whatever that's supposed to mean it's a term and standard Dershowitz simply made up that has no Constitutional support.
The article linked above is a more thorough dissection, easily dismissing not just Dershowitz but the Trump team's brief, which relies on arguments rooted in English common law (specifically William Blackstone), which I guess isn't surprising given the United States' Constitution's lack of support.
In short, the brief starts off by asserting that the "Framers restricted impeachment to specific offenses against 'already known and established law,'" and footnotes that to Blackstone's Commentaries on the Laws of England. The Just Security article demonstrates how Blackstone's phrase had a particular meaning for his time and place (it didn't mean "statutes") and isn't easily transferable to 1789 in America.