Did he really say “the court system is the Constitution,” fullstop? What’s the rest of it for, then?
Plus, he sets up a straw-man that begs the question; the founders, both pro-ratification and anti-ratification were concerned that interpretation would be a major issue. This is one reason they discussed just how the constitution ought to be interpreted. They also discussed the various legitimate means of constitutional interpretation, all of which are brought up in the course.
1) each Federal official takes an Oath to uphold the Constitution, and recall that early on, the idea was that the President should use his veto power to veto unconstitutional measures (thus Washington asking for the opinion of Madison & Hamilton on the constitutionality of a Federally-chartered bank, and, unfortunately, taking the wrong advice. But even if his decision was wrong, his procedure was correct). What happened was since Jackson, first the use of the Veto power was extended to vetoing on policy grounds (arguably this is constitutional, but it was not the tradition to that point), and now these days both Congress & the President, when they feel like it, avoid the responsibility of their oaths and pass the buck, saying it is up to the Supreme Court to decide constitutionality of acts & policies. (Then the Supreme Court likewise passes the buck on a whole range of issues by having a standard of presumptive constitutionality. This is the racket the JD friend is endorsing).
2) Most importantly, covered in the lectures, various Founders – most if not all prior to ratification, and the principled ones continuing to adhere to this position post-ratification, held that it was the responsibility of the people and the states to judge whether the constitution was being followed or not. That is, constitutional interpretation was their prerogative, at least as much as that of courts or any other Federal official. The people, through the states, were, as parties to the Constitution, to determine (interpret) if a measure was pursuant to the constitution (necessary & proper meaning just that – pursuant to the constitution, not “whatever the Federal officials say is, or whatever their courts, filled with people they appointed, say is necessary and proper”), further noting – as was noted in the lecture – that nullification was intended to follow this pattern, with no (single) state necessarily being dispositive in its interpretation of the constitution, but, rather, a state nullifying a law effectively bringing it to the attention to the others for reconsideration, in which case they could join or not.
Your JD, who must have studied Contract Law at some point, is essentially arguing that an agent of a contract, rather than the contractees, is the sole and exclusive judge of whether it is being followed or not.
Or, to put it another way: as argued for in the drafting debates, and as argued for in the ratification debates, the Constitution was intended to have multiple layered defenses against attack, rather than a single failure-point.
Note also: a subtext of this course, not explicitly discussed, is that lawyers & law schools are acting as a guild, protecting their exclusive interests, in putting forward these bogus theories of constitutional interpretation/constitutional law, one that enshrines guild members as experts and de-legitimizes any outside source of judgement. So he is simply advocating the position of his own interest group of technocrats, following the long line of Progressive “scientific public policy/public administration” advocacy.