This week, Blaine Saito (Ohio State, Google Scholar) reviews a new work by Alexandra Ferrara Walker (NYU), The Durability of Tax Laws and Their Objectives, 80 Tax L. Rev. ___ (forthcoming 2026).

What makes a law obsolete? Alexandra Ferrara Walker’s piece The Durability of Tax Laws and Their Objectives offers a compelling framework for understanding which tax laws are most vulnerable to obsolescence and outlines the mechanisms through which tax laws obsolete.

Walker provides three different types of tax laws. They are, in order of risk of obsolescence: administrative tax laws, instrumental tax laws, and income measurement laws. Understanding this framework offers insight into both the risk and mechanisms of obsolescence. Walker derives this framework through looking at the realization requirement and nonrecognition provisions as well as other tax law preferences.

Administrative tax laws are those least likely to have obsolescence. Administrative tax laws arise because of information and other real world transaction cost constraints that are difficult to solve. Walker uses realization and F Reorganization nonrecognition as key examples. With realization, there are significant information constraints to valuing property when there is no disposition as a mark-to-market system requires. Further, there are costs associated in avoiding realization like liquidity concerns. Similarly, in an F Reorganization, because there is no market transaction, value is especially difficult to determine similar to the passive increase in value without realization. There are also high liquidity costs too, as shareholders really do not “cash out” in an F Reorganization.

But administrative tax laws can become obsolete if technology or other new developments solve the information and transaction cost issues. For example, the § 1031 like-kind exchange nonrecognition provision was originally an administrative tax law because of difficulties in valuing like-kind properties. But after the development of the “technology” of intermediaries, it no longer was an administrative tax law, because the intermediaries solved the valuation problems in § 1031 exchanges. The provision thus moved into a different category, that of an instrumental law.

The second set are instrumental tax laws. are enacted to change behavior or address societal goals outside the tax system. These laws include crisis-driven provisions like COVID-era stimulus measures or incentives for small business investment. Walker identifies three paths to obsolescence for instrumental laws: (1) the targeted behavior is no longer desirable, (2) the law fails to change behavior, or (3) the law succeeds so well that it is no longer needed. For instance, § 1045’s nonrecognition treatment for reinvestment in qualified small business stock may be less effective today given the shift toward pass-through entities and the limited reach of the provision.

Income measurement tax laws are the third group. These laws are the most fragile. They aim to ensure that income is measured accurately given prevailing legal and economic conditions. Walker’s example of nonrecognition treatment for acquisitive reorganizations illustrates this well. Enacted in the early 20th century, the rule responded to high tax rates and a rapidly expanding shareholder base. Today, however, most U.S. stock is held in retirement accounts or by foreign investors, and the number of corporations has declined. These changes undermine the original rationale for the rule, yet it remains largely untouched.

Walker’s analysis of why obsolete laws persist is particularly insightful. Familiar explanations—congressional inertia, time and resource constraints, and lack of urgency—are joined by more nuanced observations. Interest group lobbying plays a powerful role in preserving outdated provisions, especially when the beneficiaries are well-organized and politically influential. Information constraints also matter. Lawmakers may not realize that the conditions justifying a law have changed, or they may lack data on whether a law is achieving its goals.

Walker then outlines some of the solutions but finds that there is no one universal take here. For example, while having proactive monitoring sounds like it can solve the information and resource constraints, there is the risk of capture of monitors. Monitors may also be unable to determine what information to collect. Looking at the acquisitive reorganization law as an example, it was really hard, until people looked at the history of the law and the changing environment with ownership of stock through tax insensitive structures, that really revealed the obsolescence. But setting that up ex ante and creating a monitor who can do that is difficult.

There are also forcing mechanisms like sunsets or dynamic legislation. But these tools only work in certain narrow conditions. Sunsets, for example really only work in the situation of temporary crises and there is gaming of them as the recent OBBBA process showed. Similarly for dynamic legislation, there needs to be something easily measurable. Some of the background legal and economic factors that form a constellation that leads to income measurement rules are just not conducive to a measurement that is required in dynamic legislation.

Walker’s framework is useful because it illuminates the different ways tax laws and policies become obsolete. Having this frame allows us to interrogate why certain policies exist. That in turn drills down on highlighting the values that we are putting forward. Walker’s framework helps to provide some means by which we can discuss these matters and deliberate better. It also invites us to interrogate what it is we are doing more readily, which is generally good in democratic deliberation.

Furthermore, what it also reveals is that all of us need to think constantly about what has changed, not just in the tax law itself, but also in terms of the outside environment. How have other parts of the law and economy shifted? What incentives are working and when are they no longer needed? Are we able to measure things better so that a certain administrative rule is no longer needed? These questions not only are inherently complicated, but they also require us to get outside of our tax bubble occasionally. That makes these issues Walker raised important but also hard.

Here’s the rest of this week’s SSRN Tax Roundup:

Reven S. Avi-Yonah (Michigan), Regulatory Taxation and the Tariffs (date posted: Nov. 4, 2025)

John Azzi (Western Sydney Univ.), The Quiet Evolution Transforming Australian Jurisprudence on How to Challenge a Tax Assessment (date posted: Nov. 4, 2025)

Aditya Bamzai (Virginia), Brief of Professor Aditya Bamzai as Amicus Curiae in Support of Neither Party, Learning Resources, Inc v. Trump (date posted: Nov. 4, 2025)

Jeremy Bearer-Friend (George Washington) & Yunyao Wu (George Washington), The People’s AI: NGO Accountability Lessons from the OpenAI Board Scandal, Rethinking NGO Accountability & Regulation: Standards, Institutions, & New Frontiers (Domenico Carolei & Angela Crack, ed.) (forthcoming, 2026) (date posted: Oct. 29, 2025)

Paul M. Cathcart, Jr. (Hemenway & Barnes LLP), Allocating GST Exemption to GRAT Property After the Annuity Term, 60 Real Property, Trust, and Estate L.J. 47 (2025) (date posted: Nov. 4, 2025)

David Elkins (Netanya) & Mirit Eyal (Alabama), Toward AI Tax Personhood (date posted: Nov. 5, 2025)

Mia Galgau (National Distance Education Univ.), Tax Havens vs Tax Hells: Reconfiguring Global Fiscal Power in the 21st Century (date posted: Nov. 3, 2025)

David Gamage (Missouri) & Darien Shanske (UC Davis), NCTI is the New GILTI, and States Should Still Conform, 117 Tax Notes State 799  (Sept. 22, 2025) (date posted: Nov. 5, 2025)

Domenico Imparato (Hamburg) & Reuven S. Avi-Yonah (Michigan), A CORE Proposal for Budget Caring—Will the EU Adopt a Progressive Corporate Tax?, 53 Intertax 646 (2025) (date posted: Oct. 29, 2025)

Tarun Jain (Supreme Court of India), Tax Discrimination: Exploring the limits of ‘permissible classification’ of taxpayers in Indian jurisprudence (date posted: Oct. 29, 2025)

Arnav Jhingan (Symbiosis Law School Hyderabad), Robat Taxation: Comparative Legal Insights for India (date posted: Oct. 29, 2025)

Reinald Koch (Catholic Univ. of Eichstaett-Inglostadt) & Lukas Oblinger (Catholic Univ. of Eichstaett-Inglostadt), Effects of the Global Minimum Tax on German Corporations (date posted: Nov. 3, 2025)

Blerta Kodra & Sotiraq Dhamo, An Analysis of the Determinants of Tax Evasion in Balkan Countries: Perspective from Accounting Specialists in Albania (date posted: Oct. 31, 2025)

Georg Kofler (Vienna University of Economics and Business), Francisco Alfredo Garcia Prats (Universitat de València), Werner C. Haslehner (Universite du Luxembourg), Eric Kemmeren (Tillburg Law School), Michael Lang (Vienna University of Economics and Business), João Félix Pinto Nogueira (Cathloc University of Portugal), Stella Raventos-Calvos (Asociación Española de Aseores Fiscales), Isabelle Richelle (University of Liège), Alexander Rust (Vienna University of Economics and Business), Withholding Taxes, Losses and Territoriality -Opinion Statement ECJ-TF 3/2025 on the decision of the CJEU of 19 December 2024 in Case C-601/23, Credit Suisse Securities (Europe) Ltd v Diputación Foral de Bizkaia (date posted: Oct. 29, 2025)

Wenderson Marinho (Kadima Holding), The Architecture of Power: How Law, Tax, and Narrative are Building Flagless Empires (date posted: Oct. 29, 2025)

Jan Neckář (Masaryk Univ.) & Michal Radvan (Masaryk Univ), Chapter 6: Czech Republic (DAC7 Rules for Digital Platforms: Comparing EU Member States’ Implementation) (date posted: Oct. 29, 2025)

Doron Narotzki (Akron) & Tamir Shanan (College of Management), Catching Pokémon, Not Tax Bills, 104 Tex. L. Rev. ____ (forthcoming 2026) (date posted Oct. 31, 2025)

Doron Narotzki (Akron), A Tax in Form, a Tariff in Function: Reclassifying Digital Services Taxes to Restore Trade Law Coherence, 45 Va. Tax Rev. 53 (2025) (date posted: Nov. 3, 2025)

Ivan Oazai (Queen’s Univ.), Beyond Economic Allegiance, 75 Univ. Toronto L.J. 425 (2025) (date posted: Nov. 4, 2025)

Leopoldo Parada (King’s College London), Balancing DSTs and Geopolitics: The European Dilemma, 117 Tax Notes Int’l 1013 (Aug. 18, 2025) (date posted: Oct. 29, 2025)

Sina Rahiminejad (Wichita State), Adam Smith Canons of Taxation: An Analysis of the IRS vs. GAAP Tax Policy (date posted: Oct. 29, 2025)

Ganesh Rajgopalan (Independent), Implementing the Multilateral Instrument in India—The Notification Conundrum (date posted: Oct. 29, 2025)

Violeta Ruiz Almendral (Universidad Carlos III), Trusts and Taxes on Wealth, Taxation of Trusts, Foundations and Similar Arrangements in a Global Setting (date posted: Nov. 3, 2025)

Anthony Welsch (Univ. Chicago Booth School of Business), Riskier Together? The Effect of Combined Tax Reporting on Corporate Risk-Taking (date posted: Oct. 29, 2025)

Jian (Buck) Xiao (Hall Chadwick Melbourne) & Anna Bullimore (Ken & Co. Chartered Accountants), Deducting Hybrid Mismatch Rules – Fit for Purpose? (date posted: Oct. 29, 2025)

Jian (Buck) Xiao (Hall Chadwick Melbourne) & Anna Bullimore (Ken & Co. Chartered Accountants),Structural Choices for Expanding into the US – An Issue-Driven Analysis (date posted: Oct. 29, 2025)

Jian (Buck) Xiao (Hall Chadwick Melbourne) & Anna Bullimore (Ken & Co. Chartered Accountants) The “Matching Principle” – A Coherent Framework to Understand Division 7A (date posted: Oct. 29, 2025)

Jian (Buck) Xiao (Hall Chadwick Melbourne), A Critical Analysis and Evaluation of US and Australian Partnership Taxation Rules and Their Intersection (date posted: Oct. 29, 2025)