When someone is charged with a crime in California, the trial often depends on the strength of the evidence. However, not all evidence is automatically allowed in court. The rules that determine what evidence a judge or jury can consider are known as the laws of admissibility.
This article provides a complete overview of the admissibility of evidence in California criminal trials. It answers commonly searched questions, explains key legal standards, and highlights how defense attorneys work to exclude unlawful or unreliable evidence. If you or someone you know is facing criminal charges, understanding these rules is essential.
What Is Admissible Evidence in California Criminal Trials?
Admissible evidence refers to any proof that a court allows to be presented to the jury or judge during a criminal trial. The California Evidence Code governs what is considered admissible, ensuring that only legally obtained, relevant, and trustworthy evidence is used.
To be admissible, evidence must generally meet the following standards:
1. Relevance (Evidence Code § 210)
Evidence is considered relevant if it tends to prove or disprove a fact that matters in the case. For example:
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Security footage placing the defendant at the scene of the crime is relevant.
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A defendant’s unrelated social media post from five years ago may not be.
Even relevant evidence can be excluded under Evidence Code § 352 if its potential to mislead or prejudice the jury outweighs its value.
2. Reliability
The court must also determine if the evidence is reliable. This applies to all types of evidence, from physical items to witness statements. Evidence that is speculative, improperly collected, or based on questionable science may be deemed unreliable and inadmissible.
Examples of reliable evidence include:
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Eyewitness testimony (if the witness is credible)
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DNA or fingerprint analysis using accepted methods
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Official documents or business records
3. Legally Obtained Evidence
Even if evidence is relevant and reliable, it may still be excluded if it was obtained in violation of the defendant’s constitutional rights. California courts follow both state and federal rules that protect individuals from unlawful searches, seizures, or interrogations.
Examples include:
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Evidence seized without a warrant or probable cause (violating the Fourth Amendment)
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Confessions made without a valid Miranda warning (violating the Fifth Amendment)
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Coerced statements or fabricated police reports (violating due process rights)
When evidence is obtained unlawfully, the defense can request its suppression, meaning it cannot be used in court.
Types of Evidence in Criminal Trials
The California Evidence Code governs how various forms of evidence are treated. The most common types include:
Testimonial Evidence
Statements made by witnesses under oath, either in court or during depositions.
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Witnesses must be competent and subject to cross-examination.
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Testimony must be based on personal knowledge.
Physical Evidence
Objects such as weapons, drugs, or clothing that relate to the crime.
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Must be properly collected, preserved, and documented.
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The prosecution must prove a clear chain of custody to show the evidence was not tampered with.
Documentary Evidence
Includes contracts, medical records, bank statements, emails, and other written or printed material.
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Must be authenticated and not hearsay (unless a hearsay exception applies).
Digital Evidence
Texts, emails, GPS data, surveillance footage, or digital logs.
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Must be verified and not obtained in violation of privacy laws.
Expert Testimony
Opinions given by forensic scientists, medical professionals, or other specialists.
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Experts must be qualified and use reliable methods.
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Scientific evidence must meet the standards set by the Kelly/Frye or Daubert rules, depending on the case.
Hearsay and Exceptions
Hearsay is generally inadmissible. Under Evidence Code § 1200, hearsay is defined as an out-of-court statement offered to prove the truth of the matter asserted.
However, there are numerous exceptions, including:
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Excited utterances
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Dying declarations
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Business records
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Prior inconsistent statements
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Statements against interest
Each exception requires that certain conditions be met. The admissibility of hearsay is often a central issue at trial.
When Evidence Can Be Excluded
Defense attorneys frequently challenge evidence to prevent it from being presented at trial. This process involves various legal tools and strategies:
Motion to Suppress (Penal Code § 1538.5)
Filed when the defense believes evidence was unlawfully obtained, such as through an illegal search or an invalid arrest.
Motion in Limine
Filed before trial to ask the judge to exclude certain evidence due to its prejudicial nature or lack of legal foundation.
Chain of Custody Objections
Used to question whether physical evidence was properly handled from the time it was collected until it reached the courtroom.
Hearsay Objections
Raised when the opposing side introduces statements that fall under the hearsay rule and do not meet any exception.
Frequently Asked Questions (FAQs)
Can evidence obtained illegally still be used in court?
Generally, no. Illegally obtained evidence is subject to the exclusionary rule, meaning it cannot be used against the defendant. There are limited exceptions, such as the good faith exception, but courts typically suppress unlawful evidence.
What if the jury hears inadmissible evidence by mistake?
If inadmissible evidence is presented during trial and affects the jury’s decision, it may be grounds for a mistrial or appeal. The judge may issue instructions to the jury to disregard the evidence, but this is not always sufficient.
Who decides what is admissible?
The judge decides all questions of admissibility. Attorneys argue their positions, but the judge ultimately rules on whether the evidence meets legal standards.
Can circumstantial evidence alone lead to a conviction?
Yes. Under California law, circumstantial evidence can support a conviction if it proves guilt beyond a reasonable doubt. The law does not require direct evidence like eyewitness testimony.
Why Evidence Admissibility Matters in Criminal Defense
Admissibility rules are not just technicalities. They protect individuals from:
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Unfair trials
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Unlawfully obtained evidence
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Jury bias from irrelevant or inflammatory material
In many cases, a strong defense strategy begins with challenging the prosecution’s evidence. Keeping unreliable or illegally obtained evidence out of court can dramatically change the outcome of a case.
Conclusion
Understanding the admissibility of evidence in California criminal trials is critical for anyone involved in the criminal justice system. Whether you are a defendant, a family member, or simply researching the law, it’s important to know that courts are required to apply strict standards to protect fairness and due process.
From relevance and reliability to constitutional protections, the rules of evidence shape the foundation of a fair trial. Skilled criminal defense attorneys use these rules to advocate for their clients and ensure justice is served.
Need Help With a Criminal Case?
If you are facing criminal charges or believe your rights have been violated through the use of illegal evidence, Southwest Legal is here to help. Our experienced criminal defense attorneys understand California’s complex rules of evidence and will fight to ensure you receive a fair trial. Don’t wait. Call us today for a confidential consultation and let us help protect your future.
