A judge's written order allowing police to take a person's blood as evidence.

"Judge's written order" matters because officers usually need probable cause and court approval before forcing a blood sample. "Take a person's blood" means a medical-style blood draw, which is more intrusive than a breath test and can reveal blood alcohol concentration, drugs, or both. "As evidence" means the sample may be used in a criminal case, an administrative license case, or a civil injury claim after a wreck. The warrant should be based on sworn facts, not guesswork, and the police still have to follow proper collection, storage, and chain of custody rules.

In practice, a blood draw warrant can make or break a DUI-related injury case. A valid sample may help show impairment after a head-on crash on a narrow road or a serious collision in a restricted commuter corridor near Idaho Falls. But shortcuts happen. If the warrant was unsupported, too broad, stale, or executed improperly, a lawyer may challenge the blood evidence through a motion to suppress.

In Idaho, Idaho Code § 18-8002 (implied consent) ties chemical testing to DUI investigations and license consequences. After Birchfield v. North Dakota (2016), forced blood draws generally require a warrant unless a recognized exception applies. That matters in injury claims because weak blood evidence can change settlement value, fault arguments, and credibility.