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Chain of Custody and Why It Is Important in a Criminal Case

Chain of custody refers to the documentation that establishes a record of the control, transfer, and disposition of evidence in a criminal case. Evidence in a criminal case may include DNA samples, photographs, documents, personal property, or bodily fluids that were taken from a defendant or discovered at the scene of an alleged crime.

To prove someone guilty, a prosecutor must prove that the evidence presented in court is the same evidence that was recovered at the scene of an alleged crime. They must be able to show that the evidence was handled properly and was not contaminated or tampered with. If law enforcement does not properly handle evidence, the evidence can be challenged on the grounds that it was tampered with, that test results are faulty or inaccurate, or that evidence was planted at the scene of a crime. 

Because criminal prosecutions rely on evidence gathered by police officers, it is typically prosecutors who must establish chain of custody.

Proving chain of custody can be difficult. If law enforcement does not do it correctly, chain of custody can be successfully challenged in a criminal case. Challenging chain of custody can be a successful defense strategy to eliminate evidence that might be used to convict a defendant.

A defense lawyer who successfully challenges the chain of custody can ask to have evidence declared inadmissible. If the judge finds that certain evidence is not admissible, the prosecutor might not have enough evidence to continue with the case.

Why Is Chain of Custody Important in a Criminal Case?

When deciding whether a defendant is guilty, judges and juries evaluate cases based on the evidence presented in court. They are not permitted to conduct their own investigations. Allowing judges or juries to base their decisions on evidence that is tainted, unreliable, or has been tampered with would undermine the integrity of the judicial system.

Chain of custody issues are particularly important in cases involving drugs, guns, or samples that have been tested for the presence of drugs or alcohol to prove intoxication. To prove chain of custody, prosecutors must present documentary and testimonial evidence to establish that the item presented at trial is the same item that was in the possession or taken from the defendant.

In a typical case, a police officer will collect evidence at the crime scene and give it to a forensics technician. The technician analyzes the evidence, for example, by testing a blood sample for the presence of alcohol or other intoxicating drugs, collecting fingerprints, or verifying that a substance collected at the scene is, in fact, an illegal drug. The forensic technician must document any tests that were performed on the evidence. When he has finished testing the evidence, he turns it over to an evidence clerk, who stores the evidence until it is needed for another test or to be presented at trial.

What Is Included in an Evidence Log?

To prove chain of custody at trial, law enforcement must be able to identify, at all times in the chain of custody, a particular person who is in control of a piece of evidence. This is done through an evidence log.

A typical evidence log will include the date and time the evidence was collected, the name of the investigator, the location where the evidence was collected, the reason the evidence was collected, relevant serial numbers, a description of the evidence, and the method that was used to collect the evidence. The log should also include signatures of the people who were in possession of the evidence, the date and time the evidence was transferred, the manner in which the evidence was transferred, and the security conditions while the evidence was being handled or stored. 

Any time evidence is examined by a forensic technician, the examiner must list everyone who came in contact with the evidence and everything that was done to the evidence.

Challenging Chain of Custody in a Criminal Case

A defendant can challenge the chain of custody of a piece of evidence by questioning whether the evidence presented at trial is the same evidence as what was collected at the scene of the crime.

If there are any discrepancies in the chain of custody and law enforcement cannot prove who had the evidence at a particular time, the chain of custody is broken and the defendant can ask to have the evidence declared inadmissible so that it cannot be used to try to convict the defendant.

To prove chain of custody, prosecutors must present evidence that proves: (1) the evidence is what the prosecutor claims it is (e.g. that the white power is, in fact, cocaine, or that the blood sample actually came from the defendant); (2) continuous possession of the evidence from the time it was seized until it was presented in court; and (3) that the evidence remained in substantially the same condition from the time each time it was transferred.

The chain of custody can be broken if a custody form is labeled incorrectly, if a transfer of evidence takes an unreasonable amount of time, or if there is reason to believe the evidence was tampered with. 

Even if there is sufficient testimony that evidence is what it purports to be and testimony has been offered to prove the chain of custody, discrepancies as to chain of custody can still be challenged and a judge or jury can use those discrepancies in assessing the weight and credibility of evidence after it has been admitted.

Just Criminal Law Protects Your One Shot at Justice

If you have been charged with a crime in or around Gillette, Wyoming, you need an experienced team of criminal defense professionals on your side, fighting to protect your one shot at justice.

Learn more about our founding attorney, Christina L. Williams, and her team of criminal defense professionals, the cases we handle, and why clients choose us, then contact Just Criminal Law today to schedule your personalized case review and strategy session.

DISCLAIMER: The information contained in this article is offered for educational purposes only. This information is not offered as legal advice. A person accused of a crime should always consult with an attorney before making decisions that have legal consequences.

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