The role of DNA Evidence in Criminal defense Cases: Pros & Cons

Ambeaulaw Firm

June 10, 2025

Table of Content

DNA evidence has changed the way criminal cases are investigated and tried. It gives law enforcement and defense teams a scientific way to link people to a crime or clear their names. But while DNA can be helpful, it also comes with challenges. At Ambeau Law Firm, our attorneys break down the strengths and weaknesses of DNA evidence and how it can be used in building a strong defense. If you’re facing charges where DNA has been used against you, we’re here to fight for your rights.

What Is DNA Evidence and Why Does It Matter?

DNA, for deoxyribonucleic acid, can play a major role in showing whether someone was involved in a crime. Since every person’s DNA is unique, it’s often used to help identify suspects or clear innocent people. DNA fingerprinting work by examining a person’s genetic material to create a unique DNA pattern. This pattern is then compared to DNA found at the crime scene to see if there’s a match or to rule someone out.

How DNA Is Tested in a Lab

DNA testing is done in different ways depending on the amount and quality of the sample. The most common testing methods used in court include:

1. STR Testing (Short Tandem Repeat)

This is the most reliable and widely used method. It compares specific parts of DNA that tend to repeat. If enough of these match between the sample and a suspect, it could be considered a match.

2. Mitochondrial DNA Testing

This method is used when the sample is old or degraded. It uses DNA passed down from the mother, and it’s less specific than STR testing.

3. Touch DNA

This involves analyzing tiny traces of skin cells left behind after touching something. While this method can be useful, it’s also more likely to lead to contamination or false results.

Pros of DNA Evidence in Criminal Law

DNA has helped law enforcement and criminal defense attorneys solve many crimes and clear many innocent people. Here are the key advantages:

1. High Level of Accuracy

When collected and tested properly, DNA can be incredibly accurate. It helps confirm whether someone was involved in a crime—or if they were wrongly accused.

2. Exonerating the Innocent

One of the most powerful uses of DNA is helping to free people who were wrongly convicted. New DNA testing has led to hundreds of exonerations in the U.S. alone.

3. Solving Cold Cases

Because DNA doesn’t degrade quickly, it can still be used years after a crime was committed. In some cases, cold cases have been solved decades later.

Cons of DNA Evidence in Criminal Law

Despite its strengths, DNA is not perfect. It’s important to understand the risks and problems that can come with using DNA in court.

1. Mistakes in Collection

If DNA is collected in a careless way—such as using dirty tools or failing to wear gloves it can easily become contaminated.

2. Chain of Custody Issues

Every step of handling DNA must be tracked. If someone mishandles the sample or forgets to document a step, the entire sample could be challenged in court.

3. Mixed Samples

In crimes involving multiple people, a sample might include DNA from more than one person. These cases, it’s hard to say for sure whose DNA is being tested.

How Criminal Lawyers Challenge DNA Evidence

A good criminal defense attorney won’t just accept DNA evidence at face value. Instead, they’ll question every part of it from how it was collected to how it was presented in court.

Here’s how lawyers challenge DNA evidence:

1. Asking Where the DNA Came From

Was the DNA found in a private place or a public one? Could it have gotten there for innocent reasons?

2. Checking the Chain of Custody

Was every step in handling the DNA documented? If not, the sample might have been contaminated or tampered with.

DNA in Criminal Cases in Baton Rouge

In Baton Rouge and throughout Louisiana, DNA has played a major role in both convicting and freeing people. But not every lab or police department gets it right.

At Ambeau Law Firm, our team has years of experience examining DNA evidence. We’ve seen cases where DNA was misread, mishandled, or simply didn’t prove what the prosecution claimed. We use expert witnesses, independent labs, and careful legal review to uncover the truth—and protect our clients.

FAQs: DNA Evidence in Criminal Cases

Q1: Can DNA evidence be wrong?
Yes, mistakes in collection or testing can lead to false results.

Q2: Do I need a lawyer if DNA is used in my case?
Yes, a criminal defense attorney can challenge DNA issues in court.

Q3: Is DNA enough to convict someone?
No, other evidence is usually needed to prove guilt.

Final Thoughts

DNA evidence can help find the truth but only when handled carefully. From serious criminal charges to wrongful arrests, the way DNA is used in court can make or break a case.

That’s why lawyers for criminal cases need to understand the science, the law, and the risks that come with it. At Ambeau Law Firm, we know how to question faulty evidence, hold labs accountable, and fight for your rights every step of the way.
https://www.ambeaulaw.com/

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Meta Description: Find out how DNA evidence works in criminal cases. Get clear answers on its accuracy, limits, and how lawyers for criminal cases can help.
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