The Law From The Bottom
The TL;dr version is lower courts don't write opinions, so it's hard for scholars to figure out what they're doing from a distance, and that they don't really apply doctrine as much as get along and keep the wheels grinding. But at least Miller recognizes that this is the world of law that humanity deals with, rather than the rarified (and far more convenient) world of Supreme Court opinions.
In the words of a friend of mine, who worked for years at a very prominent public interest law firm in the South, "everyone is overlooking everything." By this, I mean that the adjudication portion of the criminal procedure syllabus for the most part leaves students with no idea what goes in the sorts of low-level criminal courts so nicely described by Amy Bach in her book "Ordinary Injustice," which might be thought of as a journalistic follow-up to Malcolm Feeley's pathbreaking work, "The Punishment is the Process."
I'm going to hazard the thesis that the reason we have no idea what goes on in the courts that process the bulk of our criminal cases is an "elite" focus on doctrine. First, these courts are largely invisible to "doctrine." They do not produce many opinions, their other operations are hard to access from the comfort of a law-school office or library, and so there is a paucity of materials readily at hand produced by the courts. Because of our reliance on "well reasoned opinions" (or at least pedagogically-useful-badly-reasoned ones), the gold standard for teaching criminal procedure is either the elite federal court system, or the differently elite state appellate court system, which do produce opinions that are readily accessible from a computer or library.
Second, state trial and (especially) municipal courts are often bereft of "doctrine." There is little doctrine in municipal court, where lawyering depends upon interpersonal interactions between members of the court "workgroup" (as the sociologists put it). In these courts, appeals to doctrine may actually be counterproductive: a nuclear option utilized only when workgroup relationships break down or do not yet exist.
What makes this matter is that Miller isn't speaking to the obvious, and perpetually boring, scholarly output, law review articles, that serve no discernable purpose beyond demonstrating worthiness of tenure. He's talking about what the syllabus should cover in a law school criminal procedure class.
Casebooks, and thus discussion, questions, tests and papers, tend to fixate on the big cases, the broad doctrine, from which criminal law is comprised. And it must, if someone is to learn what it is criminal law is meant to look like. It's up to its eyeballs in doctrine, even if its primarily honored in the breach. But the individual holdings of Supreme Court decisions are not merely kinda puny in the trenches; they're largely ignored.
"Elite" court decisions come with a remarkably clean and clear set of facts, which means that they've made a decision along the way to "find" some facts and not others, where the evidence could have gone either way and presented a monumental headache until the case reached the stage where inconvenient facts simply disappear.
Law students tend not to realize how ambiguous and convoluted the law is in the trenches, because they only see decisions where all the conflict is sanitized into a nearly obvious state of existence. Cases are never as clean in the trial courts. Facts are in dispute, and there are usually some fine arguments either way. While facts must be found in order to achieve a result, that doesn't make the "found facts" actual facts, but merely the facts the finder prefers.
By the time a case makes it up a few levels, assuming it does as few cases go beyond one appeal as of right, facts are presented as indisputable. Opinions recite them as a given, as if there could be no real dispute what happened. This is a beloved, if not necessary, legal fiction.
In the trenches, little is clear. Lawyers for both sides fight over the most trivial of details and interpretations. Lawyers offer wholly different, completely irreconcilable versions of events. Neither judges nor juries have a magic power to figure out which, if either, is true. It's ugly. It's messy. It would make for terrible pedagogical fodder because there is no real way to arrive at correct solution.
And so, students are handed a world of law that doesn't exist and they will likely never experience. To the law student, the world of law is the cleansed Supreme Court version, not the stench of conflict and sweat of a criminal trial court. The student is taught black letter law, doctrines best suited to the opening of an elite court opinion that means little to a trial judge. Ironically, the trial judge will make life and death decisions in less time than it takes to write a blawg post, and often with less thought.
Amy Bach, in her seminal work Ordinary Injustice, recognized that the real work of law grinds out in a mindless, nasty, brutish fashion. Even though Miller seems to say that lawprofs do their students, and their scholarship, no good by spending all their time in the world of elite law as opposed to the place where the rest of us dwell, it's unclear whether this epiphany helps scholars to find their way to the courthouse.
They wouldn't like it there anyway. It's filled with vulgar lawyers and poorly dressed defendants, overworked judges, too many of whom mail it in because they've come to view their jobs as keeping the wheels grinding or getting the bad guys out of their courtroom. That's the law, and I doubt there are many lawprofs who even realize it, no less have the capacity to teach it.
And yet they keep churning out new lawyers to work in the trenches who think the law happens the way it's described in Supreme Court opinions.