It might seem easy for the state to win a case where the prosecutor has a blood or urine test result. But remember one of the major themes of the criminal justice system: don’t jump to conclusions. Just because the other side has the result doesn’t mean it comes into evidence. Among the many hurdles to getting a conviction, the one called “chain of custody” might be the hardest for the state to clear.

Chain Of Custody Defined…and the Reason for It

To protect DUI/DUAC suspects from convictions based on invalid or contaminated blood or urine samples, our courts require the state to prove the samples weren’t tampered with. This is the “chain of custody”: the state must identify the people who handled the sample from the time it was taken until the time it got tested.

The consequences can be a game-changer. Without an adequate chain of custody, the test result is inadmissible.

It’s a simple concept, but it can create insurmountable problems for the state to get the test results into evidence. Let’s talk about that.

How It Works

The state must prove the identity of those who took, labeled, sealed, transported, or handled the blood or urine in any way.

Here’s the complication for the state, which creates an opportunity for a skilled DUI/DUAC defense attorney to keep the test result out. At trial, the state has to get most, if not all, these witnesses to testify about handling the sample. Some of them work in the healthcare field, which makes it hard to get them to court. And usually the samples are tested at the state crime lab in Columbia, which can also make it hard to get those witnesses to trial. For example, consider who handles the typical blood test:

  • The officer requests it. He must testify.
  • A nurse draws the sample. She must testify. And if all she can do is “assume” she did it without remembering specifically how, the result might get tossed.
  • The officer takes the sample. He’s got to prove where he put it and who else handled it after that. That could involve evidence officers or office staff.
  • The sample goes to the state crime lab. Once delivered, the lab must prove who handled it and what those people did with it, just like the officer.
  • The tester tests the sample. The state crime lab toxicologist who actually tests the DUI blood or urine sample must testify about the test method and results.

With all these moving parts, a lot could go wrong for the state. But the law’s tricky. You need a professional to track the chain of custody and pounce on broken links in the chain to give you a shot at keeping out the results.

You’ve Got to Have Plan B

Even if the blood or urine test comes into evidence at your DUI or DUAC trial, it’s still about impairment. You need a wise, experienced DUI lawyer who can develop plan B: how to explain away those results in the face of evidence showing you weren’t intoxicated.

It can be done. If you need to find out how, check out our free report on these cases that might answer a lot of your other questions, then start a live chat to schedule a free meeting to talk about your defenses. The surest way for the officer to get a conviction is if you don’t try, and knowing you have a good lawyer working hard on your case will give you peace of mind that’s priceless—because the stakes are high.


Rob Usry
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Rob is a Spartanburg personal injury lawyer. Rob also practices as a workers' compensation attorney.