I first met — no, saw — Al Warren in the fall of 1979, while I was sitting on the floor in the back of one of our large lecture halls, watching him teach basic tax. Why was I there?

I was then a 2L, pursuing in parallel a Ph.D. in economics, and hoping to become an academic, indeed, with taxation as one of my fields. I was then taking basic tax from the eminent Stanley Surrey, but one of my classmates (now my wife, whom I always listen to) kept telling me about her amazing tax prof who was visiting from Penn. So, I had to see for myself.

‌“No wonder that, for over four decades, Al Warren’s tax classes were often  oversubscribed and always adored.”

I remember that class to this day, the best I’ve ever seen and something I could never hope to match. It was lively. Engaging. But most of all, it was clear. The examples were vivid, to capture the mind and implant in the memory, and they were precise. The simple numbers on the blackboard, the story, the whole package. No wonder that, for over four decades, Al Warren’s tax classes were often oversubscribed and always adored.

Alvin C. Warren, who is retiring at the end of spring semester, has been the Ropes & Gray Professor of Law at Harvard Law School, where he has taught since 1979. In 2016, Al received the National Tax Association’s Holland Medal, the lifetime achievement award in the field. This honor primarily reflects Al’s contributions to the scholarly community. The same clarity in thinking and communication that I saw that day in the classroom is a signature of his writing. Its other notable feature is the way he always gets to the bottom of things, untangling every strand and vanquishing every fuzzy notion, bringing the captive into sharp focus so that it can then be embraced, rejected, or at least subjected to intelligible disagreement. 

Al has taken on some of the biggest and most complex questions in the field. He was a leading player in the ongoing debate about whether income or consumption was the most appropriate base for personal taxation. This choice is incredibly important for administration because the difference between the two tax bases, involving how to tax capital income and related changes in wealth, accounts for most of the complexity in modern tax systems. It has efficiency implications regarding incentives to work and save. And many, including Al, also see this choice as central to the fairness of the tax system.

Al’s clarity and analytical depth have also illuminated our understanding of the relationship between corporate and shareholder taxation, including in his prominent project with the American Law Institute. Recognizing the intimate connection between the two subjects (after all, corporations are not real people but mere artificial entities that act on behalf of their owners, the shareholders), Al was one of the pioneers involved in working out how various systems might be devised to better integrate the two systems and then in analyzing the virtues and shortcomings of the different options.

International taxation, itself often involving interactions between the taxation of corporations and their shareholders, is a daunting subject not only because of its practical complexity but also because of the interests of competing sovereigns. Here Al focused on problems of discrimination, including as it is addressed in the European Union. Al also took on, even before it was cool, the highly complex subject of the taxation of financial contract innovation that surged decades ago and continues unabated.

I am most personally grateful for Al’s interpersonal and institutional contributions. When I joined the Harvard Law School faculty in 1982, Al became my instant mentor. Not only did he give comments generously, but his encouragement — the way he delivered it — made a big impression.

More broadly, Al was the chair of the HLS tax department for four decades. Some might ask: What tax department? HLS has no departments. True enough. But in many respects, HLS needed one and Al created and successfully ran it his entire time here. He did all the things we really needed — which includes feeding into the decanal team assembling course schedules each year — and nothing else! We had exactly the necessary number of meetings or other communications, with Al as the hub. Everything happened that needed to happen, and always on time.

One of Al’s most important contributions has been to the broader academy of tax law professors. For decades, Al ran a small annual conference. The attendees were leading and rising junior scholars. Half presented papers (assembled in a hefty volume that all read in advance) and half were designated commentators, a task taken very seriously. These gatherings created a regular, intensive exchange of ideas among top academics on important subjects in the field. They introduced these ideas to other professors earlier in their careers, bringing them into the orbits of the broader discourse. And, if you were writing a paper you hoped to present in this forum, the incentives to do your best work could not be higher. This audience would read more carefully and criticize more thoughtfully than anyone who would come later; subsequent publication was a detail. One more thing: At every session, on every paper, Al delivered a pointed list of questions and comments. Some were deep and substantive, but most notable were the many constructive suggestions offered to the more junior participants about how to improve their work.

The recurring themes are clear, as clear as Al Warren himself: Getting it right. Communicating crisply. Encouraging others. Giving generously.

Louis Kaplow ’81 is the Finn M. W. Caspersen and Household International Professor of Law and Economics at Harvard.