Bitcoin Custody Failure Modes: A Taxonomy for Professional Interpretation

Abstract

Bitcoin custody systems are designed by individuals with full contextual knowledge and later encountered by others—executors, trustees, attorneys, heirs—who must interpret and operate these systems without the original owner present. This interpretive gap produces recurring failure patterns that persist even when custody components technically exist. This paper presents a taxonomy of failure modes observed in Bitcoin custody systems when those systems are encountered under stress conditions including death, incapacity, device loss, and institutional failure. The taxonomy distinguishes between legal authority and cryptographic access, between security and survivability, and between documentation that enables action and documentation that merely describes existence. Seven failure mode categories are examined: (1) documentation without usability, where correct and comprehensive records nonetheless fail to enable execution; (2) time as an active dependency, where dormant systems degrade through institutional change, memory loss, and technological obsolescence; (3) dependency overlap, where apparently redundant components share hidden common roots; (4) partial access traps, where incomplete recovery attempts constrain or block subsequent paths; (5) authority-access misalignment, where legal entitlement and operational capability diverge; (6) coordination failure, where distributed control prevents action when parties cannot align; and (7) delay-induced state changes, where outcomes differ based on when recovery is attempted. The paper provides canonical vocabulary for professional communication about custody situations and offers a scenario reference for modeling system behavior under stress. It is intended as a descriptive reference for fiduciaries, estate planning attorneys, and advisors who encounter Bitcoin custody systems in professional contexts. The paper does not provide recommendations, evaluate custody arrangements, or establish standards of care.