## Facts

- Charles H. Cahan was among multiple defendants prosecuted for conspiracy to violate California Penal Code § 337a (horse-race bookmaking-related offenses).
- The prosecution relied mainly on (1) recorded conversations captured by covert microphones installed in defendants’ residences and (2) physical evidence seized during warrantless entries and arrests.
- Police officers entered a residence at night through a window, placed a listening device inside, and wired it to recording equipment located offsite; conversations were recorded and transcribed over weeks.
- Officers later installed similar devices in another residence using the same method and continued monitoring and recording.
- Police conducted additional warrantless break-ins at residences, including forced entries (kicking in doors and breaking windows), followed by arrests and seizures without warrants and often without a prior demand for admittance.
- After a bench trial, Cahan was found guilty; the court granted probation conditioned on county jail time and a fine, and denied a new trial.
- Cahan appealed the probation order and the order denying a new trial.

## Issues

1. Whether evidence obtained by searches and seizures that violate constitutional guarantees and related statutes should be admissible in California criminal prosecutions.
2. Whether California should abandon prior precedent admitting illegally obtained evidence and instead adopt an exclusionary rule.

## Decision

- The California Supreme Court, by a divided vote, reversed the order granting probation and the order denying a new trial as to Cahan.
- The court held that evidence obtained in violation of constitutional guarantees against unreasonable searches and seizures is inadmissible in California courts.
- Because the conviction rested primarily on unlawfully obtained evidence, the judgment-related orders could not stand.

## Legal Principles

- Evidence secured through unreasonable searches and seizures in violation of constitutional protections must be excluded from criminal trials in California.
- Exclusion operates as a judicial rule of evidence grounded in state constitutional and statutory protections, not merely as a remedy against the offending officers.
- Civil damages, administrative discipline, and criminal sanctions against officers were deemed inadequate to deter unlawful searches and seizures; exclusion is required to remove incentives for such conduct.
- Courts compromise judicial integrity when they admit the fruits of unconstitutional law enforcement actions and thereby participate in the rights violations.
- Prior California precedent permitting admission of illegally obtained evidence was overruled to the extent inconsistent with the exclusionary rule.

## Conclusion

The court adopted a state exclusionary rule barring evidence obtained through unconstitutional or otherwise illegal searches and seizures, and it reversed the probation and new-trial orders because the prosecution’s case depended largely on evidence obtained by warrantless break-ins and covert surveillance.


People v. Cahan, 44 Cal. 2d 434, 282 P.2d 905 (Cal. 1955)