United States v. Cone, 2017 U.S. App. LEXIS 16170

Officer Maher observed Cone's pickup with a nonfunctioning license-plate light and followed it to a motel parking lot; about two minutes elapsed from observation to contact.
Maher approached, asked for license, told Cone about the tag-light violation, and asked whether Cone had been in trouble or to prison before; Cone answered yes and falsely said it was for money laundering.
Maher also asked briefly what Cone was doing at the motel.
Maher planned to run a computer warrant/background check and asked Cone to step out of the vehicle for officer safety; when Cone exited, Maher saw the butt of a pistol under the console.
After securing the firearm, another officer detected marijuana odor, opened the passenger door, and found a backpack with marijuana, methamphetamine, scales, and small bags.
Cone moved to suppress the evidence; the district court denied the motion. Cone pleaded guilty to possession with intent to distribute, reserving the right to appeal the suppression ruling; this appeal followed.

Issue	Cone's Argument	Government's Argument	Held
Whether officer’s questions about criminal history during the traffic stop exceeded the scope of the stop under the Fourth Amendment	Questions about criminal history were unrelated to the tag-light stop and thus unlawful	Criminal-history inquiries are negligibly burdensome, relate to officer safety, and are permissible	Court held questions about criminal history were reasonable and lawful
Whether asking about travel plans (“What are you doing here?”) unlawfully expanded the stop and tainted evidence	Travel-plan question was unrelated because Cone had reached his destination; thus any unrelated questioning violated the stop	Even if the question were improper, Cone must show but-for causation between that question and discovery of evidence; the travel question did not cause discovery	Court did not decide the travel-question’s legality but held Cone failed to show but-for causation, so suppression not warranted

Rodriguez v. United States, 135 S. Ct. 1609 (2015) (traffic-stop scope; unrelated questioning may not measurably extend stop)
United States v. Holt, 264 F.3d 1215 (10th Cir. 2001) (en banc) (officer-safety justification for criminal-record and warrant checks)
United States v. McNeal, 862 F.3d 1057 (10th Cir. 2017) (standard of review for suppression rulings)
United States v. Sanchez, 608 F.3d 685 (10th Cir. 2010) (but-for causation required to suppress evidence as fruit of unlawful conduct)
Hudson v. Michigan, 547 U.S. 586 (2006) (but-for causation is necessary for suppression)