He will blush when he reads this, and it is true that I am his friend and have the bias of a friend (and fellow political scientist). But his stature and depth are also evident to all those who have served with him or appeared before him. I write about Katzmann because he has written a new book, called Judging Statutes, that is both a tour de force and must reading for anybody following a particularly critical case, Halbig v. Burwell, that I have written about before, and that may pose the greatest challenge yet to the full implementation and future of the Affordable Care Act.

The underlying point of Judging Statutes is that the American constitutional system requires a deep respect among the institutions of governance—which includes a respect by Congress and the courts for the key role that executive-branch officials play in their front-line role of interpreting the meaning and intent of the laws Congress passes in order to implement them; a respect by Congress for the difficulty of that executive role and for the role of the judiciary as independent arbiter; and very importantly, the respect of judges for the inherently political nature of Congress, and the difficulty and messiness involved in building coalitions and passing statutes. The latter may be distasteful and often worthy of ridicule, but it is baked into the constitutional order.

As Katzmann notes, from the beginning the framers understood that the nature of the legislative process would make statutes often unclear and murky for interpretation. Madison wrote in Federalist No. 37:

All new laws, though penned with the greatest technical skill, and passed on the fullest and most mature deliberation, are considered as more or less obscure and equivocal, until their meaning be liquidated and ascertained by a series of particular discussions and adjudications. Besides the obscurity arising from the complexity of subjects, and the imperfection of the human faculties, the medium through which the conceptions of men are conveyed to each other, adds a fresh embarrassment.

It is up to judges frequently to judge the meaning and import of statutes that are regularly subject to more than one interpretation—because laws by nature, as Madison said, are often obscure, equivocal, murky. What to do? Katzmann notes that since the 16th-century English decision known as Heydon's Case, the dominant mode has been to look at the purpose of the laws, to look carefully at what the legislature intends, to, in the words of that decision, "suppress the mischief and advance the remedy." Learned Hand wrote:

All [legislators] have done is to write down certain words which they mean to apply generally to situations of that kind. To apply these literally may either pervert what was plainly their general meaning, or leave undisposed of what there is every reason to suppose they meant to provide for. Thus it is not enough for a judge just to use a dictionary. If he should do no more, he might come out with a result which every sensible man would recognize to be quite the opposite of what was really intended; which would contradict or leave unfulfilled its plain purpose.

It is true that it is not always possible to come up with a definitive interpretation of what Congress intended. One of the most compelling parts of Katzmann's book is his account of three decisions that went to the Supreme Court from appeals courts, in one of which the judgment of Katzmann and his colleagues on the Second Circuit was overturned, that show the ways in which dutiful judges can come to opposite conclusions. But in most controversial cases, there are clear ways to look at legislative history, the words of a bill's architects or managers, and the overall body of the law to divine the plain purpose. And, as Katzmann writes, "At times it is difficult to ascertain purposes, and the search for purpose as to particular statutes, may be elusive. But to jettison the inquiry altogether, because of the difficulty in particular cases, means that judges will interpret statutes unmoored from the reality of the legislative process and what the legislators were seeking to do." To anyone who has spent time in Congress or any legislative body, who understands the fundamentals of the politics of a legislature, Hand and Katzmann are compelling.