How Do You Challenge the Evidence in a Sexual Assault Case?

 Posted on July 14, 2026 in Sex Crimes

Challenging the evidence in a sexual assault case is an important part of building a strong defense. The state has to prove every element of the offense beyond a reasonable doubt. And that standard applies to every piece of evidence they plan to use against you. Evidence can be challenged in many ways, from questioning how it was gathered to attacking its reliability in court. If you are facing a sexual assault charge in 2026, a San Antonio, TX sexual assault defense lawyer can review every piece of evidence in your case and find the strongest possible arguments to fight back.

How Can Physical and Forensic Evidence Be Challenged in a Sexual Assault Case?

Physical evidence is often the centerpiece of a sexual assault prosecution. DNA evidence in particular can carry enormous weight with a jury. But physical evidence is not perfect, and there are real ways to challenge it.

Chain of Custody Problems

Every person who handles physical evidence after it is collected has to be documented. This is called the chain of custody. If evidence was not properly logged, stored, or transferred at any point, the integrity of that evidence can be questioned. A break in the chain of custody raises doubts about whether the sample being tested is the same one that was originally collected.

Laboratory Errors

Crime labs make mistakes. Testing procedures can be flawed. Equipment can be improperly calibrated. Analysts can get things wrong. Your attorney can request the lab's records and have an independent expert review the testing to find any errors or problems. If the lab work was done improperly, the results may not be admissible or may carry much less weight with the jury.

Alternative Explanations for Physical Evidence

The presence of DNA or other physical evidence does not automatically prove a crime happened. If there was a consensual relationship between the parties, physical evidence of contact may be entirely expected and does not prove that an assault took place. Your attorney can present evidence of the nature of the relationship to give the jury an alternative explanation for what the physical evidence shows.

How Can Witness Testimony Be Challenged in a Sexual Assault Trial?

Witness testimony is subjective and can be wrong. Even well-meaning witnesses can be mistaken. In some cases, witnesses may have their own reasons to shade what they say.

Your attorney can challenge witness testimony through cross-examination in court. This involves questioning the witness to highlight inconsistencies, gaps in their memory, or reasons they might not be telling the full story.

If a witness's account has changed between their first statement to police and their testimony at trial, that inconsistency can be used to undermine their credibility. Evidence of a motive to lie or exaggerate can also be presented to the jury.

How Can the Alleged Victim's Account Be Challenged?

The alleged victim's account is typically the most important piece of evidence in a sexual assault case. Challenging that account does not mean attacking the person unfairly. It means carefully looking at the evidence for inconsistencies, alternative explanations, and reasons the account may not be fully accurate.

Your attorney will compare the alleged victim's initial statement to police with their later statements and trial testimony to look for changes or contradictions. They can examine whether physical evidence supports or contradicts the account. And they can look at the broader context of the relationship between the parties to see whether the account fits with everything else that is known.

Can Statements You Made to Police Be Challenged?

If you made statements to police after your arrest, those statements can be used against you at trial. But they can also be challenged. Under the Fifth Amendment and as established in Miranda v. Arizona, law enforcement must advise you of your rights before questioning you while in custody.

In Texas, this requirement is also codified in Texas Code of Criminal Procedure Article 38.22, which governs the admissibility of statements made by a defendant during a criminal investigation. If your Miranda rights were not properly read to you before questioning, or if the officer failed to follow the requirements of Article 38.22, statements made during that questioning may not be admissible in court. If you were questioned in a way that violated your constitutional rights, your attorney can file a motion to suppress those statements.

This is one of the most important reasons to never speak to police without an attorney present. Statements that seem harmless in the moment can be used against you in ways you did not expect, and removing them from the case can significantly weaken the prosecution's position.

Contact Our San Antonio Sex Crimes Defense Attorney Today

Attorney Lock began his career in civil litigation. He brings over 20 years of legal experience to every case he handles. He understands how evidence is built and how it can be taken apart. When you need to reach someone, a real person at Law Offices of Sam H. Lock will always answer your call, 24 hours a day, seven days a week.

Contact the San Antonio, TX sexual assault defense lawyer at the Law Offices of Sam H. Lock by calling 210-226-0965 to talk through your case today.