On July 1, Harvard Law School Professor Daniel I. Halperin retired after nearly 40 years as a law professor, including two decades as the Stanley S. Surrey Professor of Law at HLS. Below, reprinted from the Spring 2015 issue of the Harvard Law Bulletin, is a tribute to Halperin written by his colleague Alvin C. Warren, who is the Ropes & Gray Professor of Law at HLS.

Daniel I. Halperin ’61 retired at the end of this academic year after more than a half-century as a tax lawyer, professor and government official. Unlike most law professors starting out today, Dan worked as a lawyer for a decade—at the firm Kaye Scholer and in the government—before entering law teaching. Serendipitously, he became Kaye Scholer’s expert in the new field of pension law in his second year, after the sudden departure of the only lawyer at the firm with any experience in the field.

In 1967, Dan moved to Washington to join the staff of the Treasury Department’s Office of Tax Policy, which is the executive branch office responsible for tax regulations and legislative proposals. At the time, the assistant secretary of the Treasury for tax policy was Stanley S. Surrey, a legendary Harvard Law School professor who served as the principal tax policy officer for Presidents Kennedy and Johnson. (He had also been Dan’s teacher in a course on the taxation of international income.)

Although tax law is frequently contested and often political, Surrey’s rule was that his staff was to consider only the criteria of good tax policy in developing regulations and legislative proposals. Political issues were to be left to him, the Treasury secretary and the White House.

Dan flourished in this environment. Thanks to his practice experience, he played a key role in the development of the Johnson administration’s initial bill for pension security, which would evolve into the historic Employee Retirement Income Security Act, enacted by Congress in 1974.

Surrey further believed that the Treasury should not only focus on current regulatory and legislative issues, but also analyze and produce proposals for long-term reform. Dan played an important role in the evolution of these proposals, which eventually led to the Tax Reform Act of 1969. Although a lifelong Democrat, he remained at the Treasury as deputy tax legislative counsel after the election of President Nixon in order to see the proposals through to enactment.

Stimulated by his work at Treasury, Dan joined the faculty at the University of Pennsylvania Law School in 1970. His first major article as a professor, “Business Deduction for Personal Living Expenses: A Uniform Approach to an Unsolved Problem,” 122 University of Pennsylvania Law Review 859 (1974), remains a classic 40 years later.

In the presidential campaign of 1976, Jimmy Carter famously called the U.S. income tax system a “disgrace to the human race.” After the election of President Carter, Dan returned to the Treasury, first as tax legislative counsel and then as deputy assistant secretary. In those positions, he was instrumental in the formulation of the president’s 1978 tax reform proposals, some of which were enacted in the bipartisan Tax Reform Act of 1986.

In 1981, Dan returned to law teaching, this time at Georgetown, where he would remain for 15 years. He also returned to practice as a consultant for Ropes & Gray. It was during this period that Dan’s most famous article, “Interest in Disguise: Taxing the Time Value of Money,” 95 Yale Law Journal 506 (1986), appeared. Stemming from problems he had dealt with at Treasury, this article remains the seminal analysis of a series of issues that are still not fully resolved.

In 1996, Dan was appointed the first Stanley S. Surrey Professor of Law at Harvard Law School. Over the past 19 years, he has continued to write about tax law and policy, and has taught a variety of tax-related courses, covering income taxation, tax policy, pension law, and nonprofit organizations.

Throughout his long career, Dan has always been known in the tax law community for two attributes: his analytical sophistication and his generosity. No matter how difficult the problem, Dan is usually the first to see a solution (or why a solution may be impossible). This sophistication has always been coupled with remarkable generosity. When congressional staffers, young law professors or law students have asked for his help in understanding some difficult question, Dan has never been too busy to provide the requested assistance.

What are his plans for retirement? Dan has already begun work on a book on some unresolved issues in tax law and policy. Stanley Surrey would be proud.

Alvin Warren is Ropes & Gray Professor of Law at HLS, where he has taught tax law and policy since 1979.