355 U.S. 225 (1957)
A person cannot be convicted of failing to register if they had no idea the duty existed and no reason to know.
Good law. Still followed. Later cases may have narrowed it — see Scope. Binds every court in the country on the federal question it decides.
A Los Angeles ordinance required anyone convicted of a felony-grade offense to register with police if they stayed in the city more than five days. Virginia Lambert had lived there for over seven years and had a forgery conviction. Arrested on suspicion of another offense, she was charged with failing to register. The trial court would not let her show that she did not know about the requirement, and she was fined $250 and put on three years’ probation.
By 5–4, the Court reversed. Applying a registration law of this kind to someone with no actual knowledge of the duty and no showing that knowledge was probable violates due process. Conviction requires “actual knowledge of the duty to register or proof of the probability of such knowledge.”
Lambert is the oldest case here and still the reason registration systems are built around notice: signed acknowledgment forms, notification at release, and written explanations of each duty. A failure-to-register prosecution usually has to show the person was told. It is also a reminder that registration began as a general felon-registration idea, not one aimed only at sex offenses.
It did not strike down registration laws or strict-liability crimes in general. The Court stressed that the ordinance punished purely passive conduct — simply being in the city — and that legislatures keep “wide latitude” to leave knowledge out of an offense. Once a person has been told of the duty, Lambert offers little.
Last verified against the sources above on September 30, 2026.
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