All of those qualities--the deep knowledge of history, the writing skill, and the sass--are on display in his new book A Wall of Education: What the Supreme Court Really Says (And Really Doesn't) About The Separation of Church and State in Education). It's an extension/collection of his regular "Have To" History posts on the blog, where the history teacher him just has to break down significant historical stuff.
The book is a chronological collection of every SCOTUS case related to the long-storied wall between church and state where it runs through schools. That may sound like a tough row to hoe, but Koehn makes it tolerable--even entertaining--through a couple of devices.
For one, each section lets you go as deep as you like. Koehn starts with Three Big Things--the basic "what you need to know about this case" boiled down to three bullet points. Then there's the background (how we got there), the arguments, and the decision, plus why it mattered, all clearly labeled so that you can skim as you wish. At the end, he gives you the opinions and dissents from the judges themselves. With each case, you are free to dig as deeply as you wish (or not).
This is all aided by Koehn's relaxed, plain-language voice. It's pretty easy to imagine these capsuled explanations as class presentations. Take this paragraph, selected by me pretty much at random, from his discussion of Lee v. Weisman:
Justice Antonin Scalia, joined by Chief Justice William Rehnquist and Justice Clarence Thomas, had a number of problems with the majority decision, most of which centered around--wait for it-- the focus on "coercion." Being Scalia, this wasn't the only problem with the decision. Everyone participating in it was a big stinky dumb doo-doo head. But coercion came up the most in his mocking, sputtering rebuttal. (Quote from Scalia follows)
There's a lot of scholarship here, and a lot of understanding conveyed in ways that don't require you to be a legal scholar, but which makes the musing of legal scholars a bit easier to follow. Reading the volume through, in order, one gets a real education on the ubiquitous "Lemon Test," and you can see, almost in real time, the slow erosion of the wall as folks on the religious side keep probing and pushing, sometimes more honestly and sincerely than others.
Koehn divides cases into major in-depth chapters and quicky "worth a look" sidebars. It makes a great reference book for those of us who aren't lawyers, like having easy access to a legal historian who speaks regular English. I know I'm eventually going to be irritated at the lack of a table of contents or index, but there is a very handy grouping of cases by subject area in the back, as well as a list of further resources.
Koehn's own inclinations are easy to spot, but he is fair and even-handed in his treatment of the various parties in these cases (kind of like any experienced well-read professional educator handling a controversial topic). The book is self-published, but available at plenty of on-line outlets. It's a hefty 400-ish pages, but reads quickly and provides a quick look-up source for all the cases you'd want to know about. I recommend this book as a worthwhile addition to your education policy library.