Computer law was never written on a clean slate. It was assembled piece by piece as each new machine—a program, an encrypted file, a comment thread, a training dataset—arrived at the courthouse and forced a judge or legislator to decide which old legal box it belonged in. This research article traces that history as a connected argument: the fight over whether software could be copyrighted at all (CONTU and Apple v. Franklin), the forty-year war over software patents (Benson through Alice), the rise and judicial narrowing of the Computer Fraud and Abuse Act (Van Buren), the platform-liability bargain of Section 230, the DMCA's twin regimes of safe harbor and anti-circumvention, the Crypto Wars over whether code is speech, the legalization of the electronic signature, copyright turned into an engine of sharing through open source, the bottom-up birth of American data-privacy law, and the arrival of artificial intelligence. Each milestone is explained in plain language and anchored to primary authority, and the throughline is a single recurring problem: how to govern machines the law's drafters never imagined. The aim is a durable reference for practitioners, judges, founders, and policymakers who need to see the whole arc, not just the latest headline.