Problems to Look for With DNA Evidence

We’re not in the business of misleading our clients or prospective clients.

The reality is, if your accuser is threatening you with DNA evidence, you have an uphill battle ahead of you. The legal system and media have pushed the notion that there's nothing more rock-solid than this manner of proof. And these factors do play a role in how scenarios involving alleged child abuse play out. On top of that, DNA evidence is often accurate.

However, just because DNA evidence can be convincing and accurate doesn't always guarantee that your accuser (or the government agency) can prove your guilt.

There is a laundry list of problems that can detract and refute the validity of DNA evidence. From biases to analytical errors, there's any reason the credibility of these samples can crumble when put through the rigors of critical analysis.

Let's examine some of the more common mistakes made by forensic labs that we try to leverage when putting together a defense. These scenarios come from a presentation called "Forensic DNA Defense Strategies” by R. Vincent Miller, Ph.D.

Analytical Error, Fraud, or Perjury

There are instances, such as with the Houston Police Department, where unqualified people analyze samples. They reach conclusions with no scientific validity, and in this one example, it occurred in over 200 cases and ended up with the closure of the laboratory.

In West Virginia, evidence was falsified in 300 cases. Baltimore had 500 cases involving perjury.

The numbers are alarming when you think about it. Given the frequency of these kinds of situations, it's always worth investigating the legality of the evidence itself.

Excluding Evidence that Would Clear the Accused

Do you remember the Duke Lacrosse case back in 2006? An entire documentary was made about this scandal. It saw three players falsely accused of sexual assault by an exotic dancer, resulting in chaos and life-ruining ramifications.

Eventually, after an incredibly tumultuous experience, the three players accused were exonerated when the district attorney was proven to have withheld evidence.

More specifically, out of a bias on the part of the prosecution, samples were selected based on their theories of the case. This is often the reason for excluding evidence that would favor the accused.

Planting Evidence

Continuing with the theme of poor human judgment, being outright deceitful is not something that eludes those who are working within the law enforcement system.

As recently as 2018, a Baltimore police officer was found guilty of planting evidence after his body cam caught him doing precisely that.

The cruel reality is that authority figures have a lot of pressure on them to fill quotas, for instance. Or they may be working with other ulterior motives. Either way, there's a chance - albeit a small one - that they'll plant evidence.

Clerical Mistakes

Clerical errors have led to innocent people being accused and even charged with crimes they did not commit.

For instance, in Las Vegas, a man served one year in prison for sexual assault when his name was incorrectly labeled on a DNA sample. In fact, the only reason this mistake was discovered was that the defense requested a re-testing of the sample.


Look no further than the case of OJ Simpson to notice the sloppiness often displayed by field personnel – or police – when collecting and processing DNA evidence.

Here's a list of the things done wrong during the Simpson case:

  • Blood evidence swatches were placed inside plastic – not paper – containers, so the DNA could degrade.
  • Parts of the DNA evidence were collected weeks after the crimes had been committed.
  • Despite blood evidence needing to be delivered immediately to a lab for presentation, police walked around for hours.
  • Field personnel spilled Simpson's blood in the lab, where other samples would be tested shortly after.

Sometimes the defense team will look to the lab to try and discredit prosecuting evidence, but it would be less likely that any mistakes would be made there.

Conversely, looking at how the police or other law enforcement handled the sample may be a better route to a successful defense.

Understanding the Mistakes that Can Be Made with DNA

In your situation, your back is very much against the wall, even though you didn't do anything wrong.

Therefore, you must seek out different ways to defend yourself against these false allegations. That means digging deep to discredit every piece of evidence collected to hurt you.

With DNA evidence, your attorney needs to explore the above factors when establishing a line of questioning when trying to prove your innocence.

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