Kevin Dugar v. State, 629 S.W.3d 494

Around 1:40 a.m., Officer Pratt observed an SUV drifting so it partially straddled more than one clearly marked southbound lane on MLK; no other traffic was nearby.
Pratt stopped the SUV; Dugar was the sole occupant and the officer smelled alcohol, observed glassy eyes, slurred speech, and a failed HGN test; Dugar refused further field sobriety tests and was arrested.
Pratt obtained a warrant and a nurse drew Dugar’s blood; Jefferson County Crime Lab later tested the specimen and reported an alcohol concentration of 0.15 or greater.
At trial Dugar moved to suppress evidence from the stop, arguing the initial stop lacked reasonable suspicion because the lane drift was not unsafe; he also contested admissibility of the blood test, arguing inadequate collection/preservation and gaps in chain of custody.
The trial court denied the suppression motion and admitted the blood-test evidence; the jury convicted Dugar of DWI.
On appeal the Ninth Court affirmed, rejecting both the Fourth Amendment challenge to the stop and the chain-of-custody/authentication challenge to the blood evidence.

Issue	Plaintiff's Argument (Dugar)	Defendant's Argument (State)	Held
Whether the traffic stop was supported by reasonable suspicion under the maintain-a-single-lane statute	Officer lacked reasonable suspicion because crossing/straddling lanes did not endanger anyone and statute requires unsafe movement	A reasonable officer could interpret the statute to prohibit failing to stay in a single lane; straddling lanes objectively could create danger; Leming supports such an interpretation	Court held an objectively reasonable officer could have believed a violation occurred; under Heien reasonable mistake of law excused the stop; suppression properly denied
Whether the blood-test evidence was admissible given alleged defects in collection, preservation, and chain of custody	State failed to show the nurse followed proper draw procedures, vials were preserved, or an unbroken chain to the lab; gaps render samples untrustworthy	Officer and lab director testimony plus lab paperwork showed draw, sealing, preservatives, storage in locked evidence fridge, and lab identification of the specimen; any gaps go to weight, not admissibility	Court held trial court did not abuse discretion admitting the tests; gaps in chain of custody affect weight, not admissibility; issue overruled

Heien v. North Carolina, 574 U.S. 54 (2014) (reasonable mistake of law can justify a stop under the Fourth Amendment)
Leming v. State, 493 S.W.3d 552 (Tex. Crim. App. 2016) (plurality: interpretation of maintain-a-single-lane statute allowing conviction for failing to remain in a lane even if deviation is not unsafe)
Garcia-Cantu v. State, 253 S.W.3d 236 (Tex. Crim. App. 2008) (standards for inferring factual findings on suppression rulings)
Lerma v. State, 543 S.W.3d 184 (Tex. Crim. App. 2018) (bifurcated review and deference to trial court's credibility findings on suppression)
Druery v. State, 225 S.W.3d 491 (Tex. Crim. App. 2007) (authentication and trial court's broad discretion in admitting evidence)
Hartsfield v. State, 200 S.W.3d 813 (Tex. App.—Texarkana 2006) (gaps in chain of custody affect weight, not admissibility)