In California criminal jurisprudence, the pre-trial motion stage is frequently where criminal cases are won or lost. Under California Penal Code § 1538.5, a defendant has the constitutional right to move for the suppression of tangible and intangible evidence obtained as a result of an unreasonable, warrantless, or unconstitutional police search and seizure.
1. Grounds for a Penal Code § 1538.5 Motion to Suppress
Under the Fourth Amendment to the United States Constitution and Article I, Section 13 of the California Constitution, warrantless searches are per se unreasonable unless falling into narrowly defined exceptions:
- Unlawful Traffic Stops (Lack of Reasonable Suspicion): Law enforcement cannot pull over a vehicle based on an arbitrary hunch. If the initial traffic stop lacked specific, articulable facts demonstrating a Vehicle Code violation, all subsequent evidence discovered is suppressed.
- Exceeding the Scope of a Warrant: Officers executing a search warrant for stolen flat-screen televisions cannot rummage through small jewelry boxes or encrypted digital storage without specific judicial authorization.
- Coerced or Involuntary Consent: Consent given while handcuffed under the threat of arrest is legally tainted and involuntary.
2. The "Fruit of the Poisonous Tree" Doctrine
Under the landmark ruling in Wong Sun v. United States (1963), when a primary illegality occurs (e.g. an illegal pat-down search), any secondary evidence derived directly from that illegality (such as a confession, physical contraband, or lab test results) is deemed "fruit of the poisonous tree" and must be excluded from trial.
3. Pitchess Motions & Law Enforcement Credibility
Under California Evidence Code §§ 1043–1045, defense counsel can file a Pitchess Motion to compel the discovery of prior complaints in a police officer's confidential personnel file regarding excessive force, fabrication of probable cause, or racial bias. Evidence of prior dishonest reporting severely undermines the prosecution's witnesses during suppression hearings.