The Lawfare Podcast Lawfare Archive: Orin Kerr on the Digital Fourth Amendment
May 9, 2026
Orin Kerr, Stanford Law professor and leading scholar on the Fourth Amendment, discusses his book The Digital Fourth Amendment. He traces how digital data upends physical-world Fourth Amendment assumptions. He explains his Equilibrium-Adjustment Theory and how courts have adapted doctrines like Carpenter and Katz. He also covers challenges like mosaic theory, commercial data, and how scholars influence judges.
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Equilibrium Adjustment Explains Court Responses To Technology
- Equilibrium adjustment describes how courts change legal rules to restore the Fourth Amendment's prior balance when technology alters government investigatory power.
- Example: Carroll (1925) created the automobile exception because cars made warrant delays impractical.
Aim To Preserve The Fourth Amendment's Role Not Fixed Rules
- When evaluating tech-driven doctrinal change, courts should aim to preserve the Fourth Amendment's role: enough enforcement power but not so much that privacy collapses.
- Judges instinctively seek a middle ground between a police state and zero policing as technologies evolve.
Katz Replaced Physical Intrusion With Privacy Focus
- Katz reoriented the Fourth Amendment from physical intrusion to privacy by recognizing phone booth eavesdropping as a search.
- The Court treated listening to private phone calls via a taped microphone as the modern equivalent of physical intrusion.
