How Can Evidence Be Challenged in a Criminal Case?
April 17, 2025
In the criminal justice system, evidence is the cornerstone of any prosecution or defense. It shapes the narrative, influences judicial decisions, and determines whether a defendant is convicted or acquitted.
However, not all evidence presented in court is admissible, reliable, or legally obtained. Challenging evidence is a critical strategy for a defense attorney.
Evidence can be challenged in a criminal case in various ways, including legal grounds, procedural mechanisms, and practical considerations, while grounding the discussion in the state’s laws and court practices.
The Hardin Law Firm LLC defends clients in criminal cases throughout the communities in and around the greater St. Louis, Missouri area. Attorney Hardin is an experienced criminal defense attorney well-versed in a variety of areas, including assault, sexual assault, rape, theft, burglary, domestic violence, manslaughter, and murder. If you are facing criminal charges in the greater St. Louis, Missouri area, call The Hardin Law Firm LLC today to schedule a free consultation.
Evidence in Missouri Criminal Cases
Evidence in a criminal case refers to any material, testimony, or information presented to prove or disprove facts relevant to the charges.
In Missouri, evidence is governed by the Missouri Rules of Evidence, which align closely with federal standards, and by statutory and constitutional provisions, including the Missouri Constitution and the U.S. Constitution. Evidence can be categorized into several types:
Direct evidence: Directly proves a fact, such as an eyewitness identifying the defendant as the perpetrator.
Circumstantial evidence: Indirectly suggests a fact, such as fingerprints found at a crime scene.
Physical evidence: Tangible items, like weapons, drugs, or DNA samples.
Testimonial evidence: Statements made by witnesses or defendants under oath.
Documentary evidence: Records, reports, or written materials, such as police reports or contracts.
Digital evidence: Data from computers, phones, or surveillance systems.
For evidence to be admissible in Missouri courts, it must meet three key criteria: relevance, materiality, and competence. Relevant evidence tends to prove or disprove a fact in question, material evidence relates to a significant issue in the case, and competent evidence is legally permissible (e.g., not obtained in violation of the law).
Evidence that fails to meet these standards or is otherwise flawed can be challenged through various legal mechanisms.
Grounds for Challenging Evidence
Challenging evidence involves questioning its admissibility, reliability, or weight. Attorney Hardin employs several strategies to suppress, exclude, or discredit evidence. Below are the primary grounds for challenging evidence:
1. Constitutional Violations
Evidence obtained in violation of a defendant’s constitutional rights is subject to exclusion under the exclusionary rule, which prevents illegally obtained evidence from being used in court. Common constitutional challenges include:
Fourth Amendment violations (unreasonable searches and seizures): The Fourth Amendment protects against warrantless searches or seizures without probable cause. In Missouri, if police conduct a search without a valid warrant, consent, or an applicable exception, the evidence may be deemed inadmissible.
Fifth Amendment violations (self-incrimination): The Fifth Amendment protects against compelled self-incrimination. If a defendant’s confession is obtained without a Miranda warning or through coercion, it can be challenged. Missouri courts strictly enforce Miranda rights, as seen in State v. Seibert (Mo. 2004), where a confession was suppressed due to improper police questioning tactics.
Sixth Amendment violations (right to counsel): Evidence gathered after a defendant requests an attorney but is denied access may be excluded. For instance, statements made during custodial interrogation without counsel present can be challenged if the defendant invoked their right to counsel.
2. Procedural Errors
Evidence can be challenged if law enforcement or prosecutors fail to follow proper procedures:
Chain of custody issues: Physical evidence, such as drugs or weapons, must have a documented chain of custody to confirm it has not been tampered with or contaminated. In Missouri, a defense attorney may challenge evidence if there are gaps in the chain of custody, rendering it unreliable. For example, in State v. Link (Mo. App. 1998), the court scrutinized chain-of-custody issues for drug evidence, emphasizing the prosecution’s burden to prove integrity.
Improper collection or handling: Evidence collected without adherence to forensic standards (e.g., contaminated DNA samples or mishandled blood tests) can be challenged. Missouri courts require strict compliance with protocols to admit scientific evidence.
Discovery violations: Under Missouri Supreme Court Rule 25.03, prosecutors must disclose evidence to the defense in a timely manner. Failure to disclose exculpatory evidence (known as a Brady violation, after Brady v. Maryland, 1963) can lead to suppression or even dismissal of charges.
3. Relevance and Prejudice
Under Missouri Rule of Evidence 403, evidence may be excluded if its probative value is substantially outweighed by the risk of unfair prejudice, confusion, or misleading the jury. A defense attorney often challenges evidence as irrelevant or overly prejudicial. For example:
Character evidence: Evidence of a defendant’s prior bad acts is generally inadmissible unless it proves motive, intent, or identity (Rule 404(b)). In State v. Bernard (Mo. 1993), the court excluded prior conviction evidence because it risked prejudicing the jury.
Graphic evidence: Photos or videos that are excessively gruesome may be challenged if they inflame the jury’s emotions without adding significant probative value.
4. Hearsay Objections
Hearsay—out-of-court statements offered to prove the truth of the matter asserted—is generally inadmissible under Missouri Rule of Evidence 801, unless an exception applies (e.g., excited utterance, dying declaration). A defense attorney frequently challenges witness testimony or documents as hearsay.
For instance, a police report summarizing a witness’s statement may be excluded unless the witness testifies in court and is subject to cross-examination.
5. Witness Credibility and Competency
Testimonial evidence relies on the credibility and competency of witnesses. In Missouri, a defense attorney can challenge:
Witness competency: Witnesses must be mentally capable and have personal knowledge of the facts (Rule 601). For example, testimony from a child or a witness with cognitive impairments may be challenged if they cannot understand the oath or recall events accurately.
Bias or motive: Witnesses with ulterior motives (e.g., plea deals, grudges) can have their credibility impeached. Missouri courts allow cross-examination to expose bias, as seen in State v. Joiner (Mo. App. 1992).
Prior inconsistent statements: If a witness’s testimony contradicts earlier statements, the defense can introduce those inconsistencies to undermine their reliability.
The credibility of every witness is imperative to their impact on the case.
6. Scientific and Expert Testimony
Scientific evidence, such as DNA, ballistics, or toxicology reports, must meet the Frye standard in Missouri (derived from Frye v. United States, 1923), which requires general acceptance in the relevant scientific community. Missouri courts also consider the Daubert standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) for federal cases, emphasizing reliability and methodology.
Challenges to scientific evidence include:
Invalid methodology: If forensic tests were conducted improperly (e.g., uncalibrated equipment), the results can be excluded.
Expert qualifications: The defense can challenge an expert’s credentials or expertise. For example, in State v. Taylor (Mo. 2009), the court scrutinized the qualifications of a forensic analyst.
Junk science: Evidence based on discredited methods, like bite mark analysis, may be challenged as unreliable.
Procedural Mechanisms for Challenging Evidence
In Missouri, evidence is typically challenged through specific legal procedures:
1. Motions to Suppress
A motion to suppress is the primary tool for challenging evidence before trial. Filed under Missouri Supreme Court Rule 24.05, this motion asks the court to exclude evidence obtained illegally or improperly. Common bases include:
Unlawful searches or seizures.
Coerced confessions.
Improperly collected forensic evidence.
The defense must file the motion before trial, unless new evidence emerges. A suppression hearing is held, where the judge evaluates the evidence’s admissibility. For example, in State v. Sund (Mo. 1995), a motion to suppress was granted after police conducted an illegal warrantless search.
2. Objections at Trial
During a trial, a defense attorney can object to evidence as it is introduced. Common objections include:
Hearsay: “Objection, hearsay!”
Relevance: “Objection, irrelevant!”
Prejudice: “Objection, unfairly prejudicial!”
The judge rules on objections immediately, either sustaining (agreeing with the objection) or overruling (allowing the evidence). Missouri judges have broad discretion in these rulings.
3. Motions in Limine
A motion in limine seeks to exclude evidence before trial to prevent it from being mentioned in front of the jury. For example, the defense might move to exclude a defendant’s prior convictions to avoid prejudice. These motions are strategic, as they shape the trial’s narrative early.
4. Cross-Examination
Cross-examination is a powerful tool for challenging testimonial evidence. By questioning witnesses’ memories, perceptions, or motives, the defense can weaken the prosecution’s case. Missouri courts emphasize the right to confrontation under the Sixth Amendment, ensuring robust cross-examination.
5. Post-Trial Motions
If evidence is improperly admitted, the defense can file a motion for a new trial (Rule 29.11) or appeal the conviction. Appellate courts review whether the trial court abused its discretion, as seen in State v. Forrest (Mo. 2005), where an improper admission of hearsay led to a reversed conviction.
Contact a Defense Attorney Today
Challenging evidence in a Missouri criminal case is a multifaceted process that requires a deep understanding of constitutional protections, procedural rules, and strategic advocacy. By attacking evidence on grounds of illegality, unreliability, or prejudice, a defense attorney can weaken the prosecution’s case and safeguard their clients’ rights. Contact The Hardin Law Firm LLC in St. Louis, Missouri, today for guidance in your criminal case.