Not the same thing as the blood test result itself, and not just a label on a tube. A chain of custody blood sample is the documented trail showing who collected a blood sample, when it was sealed, how it was stored, who transported it, who tested it, and whether it stayed secure the whole time. The point is to prove the sample tested in a lab is the same one taken from the person, without mix-ups, tampering, contamination, or unexplained gaps.

In real life, this comes down to paperwork, seals, signatures, times, and storage steps. If one person draws the blood, another logs it, and a lab receives it later, each handoff should be tracked. If that trail is sloppy, a lawyer may challenge the evidence, the lab report, or even the reliability of the blood alcohol concentration or drug finding. A bad chain does not automatically erase a test, but it can weaken how much weight a judge, jury, or hearing officer gives it.

For an injury claim, this can matter after a crash or jobsite incident where alcohol or drugs are blamed. If a blood sample is being used to deny workers' compensation benefits in Idaho, the records behind that sample may become a key fight before the Idaho Industrial Commission in Boise. In DUI cases, Idaho's implied consent law, Idaho Code § 18-8002, and related DUI provisions under Idaho Code § 18-8004 often make blood-test handling a practical issue, not just a technical one.