Taking It Apart: Reverse Engineering, Interoperability, and the Law of Compatible Products
By Casey Scott McKay ·
Taking a product apart to learn how it works is lawful in most circumstances and unlawful in several specific ones, and the difference turns on which body of law is asked. This article separates the four regimes that govern reverse engineering — copyright, trade secret, contract, and the circumvention provisions — and explains what each permits and forbids. It covers intermediate copying and the fair use analysis that makes decompilation possible, why interfaces and functional requirements sit outside copyright protection, and how a clean room converts a legally fragile project into a defensible one. It then addresses the contractual prohibitions that appear in nearly every license, the preemption question they raise, and the narrow statutory exceptions for interoperability, security research, and repair. It closes with what a compatible-product program actually looks like.
IP and Technology > Information Technology | Article | Published 6 June 2026 - Updated 18 July 2026 | Casey Scott McKay - marksy.us
Summary. Taking a product apart to learn how it works is lawful in most circumstances and unlawful in several specific ones, and the difference turns on which body of law is asked. This article separates the four regimes that govern reverse engineering — copyright, trade secret, contract, and the circumvention provisions — and explains what each permits and forbids. It covers intermediate copying and the fair use analysis that makes decompilation possible, why interfaces and functional requirements sit outside copyright protection, and how a clean room converts a legally fragile project into a defensible one. It then addresses the contractual prohibitions that appear in nearly every license, the preemption question they raise, and the narrow statutory exceptions for interoperability, security research, and repair. It closes with what a compatible-product program actually looks like.
Keywords: reverse engineering, interoperability, intermediate copying, fair use, clean room, idea expression dichotomy, section 102b, application programming interfaces, circumvention, section 1201 exception, contractual prohibition, preemption, trade secret proper means, patent independence, repair and aftermarket, decompilation, security research, competitive compatibility, first sale, license restrictions
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