United States v. Javier Leon, 924 F.3d 1021

In March 2015 Arkansas State Trooper Olen Craig found Javier Leon stopped on an entrance-ramp shoulder; Leon said he had pulled over to call dispatch and produced his bill of lading and logbook.
Craig noted two logbook abnormalities (two weeks off duty; two-day delay before route) and asked if Leon carried drugs; Leon denied and appeared nervous, then consented to a search.
Craig inspected the cab but did not physically search the loaded trailer; he called nearby Officer Chase Melder, who arrived within minutes with a drug dog that alerted near the rear doors and about a quarter in.
Melder entered the trailer and discovered roughly 116.5 kg of methamphetamine in visible/partially covered containers near cargo Leon was to deliver at a later stop.
Leon was indicted for possession with intent to distribute, moved to suppress (arguing involuntary consent, language barrier, and an unreasonable extension of the stop), which the district court denied; a jury convicted and Leon received 180 months.
On appeal Leon challenged (1) sufficiency of evidence of knowing possession, (2) denial of suppression (alleged unlawful extension/dog sniff), and (3) rejection of a particular jury instruction about mere presence.

Issue	Plaintiff's Argument (Leon)	Defendant's Argument (Government)	Held
Sufficiency of evidence to prove knowing possession	The government lacked proof that Leon knew about the meth; control of a truck alone is insufficient, and Leon may have been a "blind mule"	Large, partially exposed quantity in truck where Leon had control supports an inference he knew about the drugs	Affirmed: a reasonable jury could infer knowledge from the large, poorly hidden drugs in Leon's truck
Motion to suppress: delay for dog sniff and voluntariness of consent	The dog sniff/arrival delayed the stop unreasonably; consent was involuntary because Leon had limited English	Officers relied on prevailing Eighth Circuit precedent allowing limited delay and Leon consented; any delay was de minimis	Affirmed: at the time no reasonable-suspicion requirement applied; consent justified the extension and any delay was de minimis; Davis good-faith precedent applies
Jury instruction: request to add mere-presence clarification	Requested specific instruction that mere presence cannot establish constructive knowledge	District court already instructed on constructive possession and defense; specific wording not required	Affirmed: no abuse of discretion; instructions adequately covered defense theory

Rodriguez v. United States, 135 S. Ct. 1609 (2015) (Supreme Court decision requiring reasonable suspicion to extend a stop for a dog sniff; changed governing law shortly after this stop)
Davis v. United States, 564 U.S. 229 (2011) (exclusionary rule does not apply when officers act in objective, reasonable reliance on binding appellate precedent)
United States v. Rivera, 570 F.3d 1009 (8th Cir. 2009) (consent to search necessarily permits extension of a traffic stop while search is conducted)
United States v. Aponte, 619 F.3d 799 (8th Cir. 2010) (additional proof required to infer knowledge from concealed drugs in a vehicle not owned by defendant)
United States v. Marquez, 462 F.3d 826 (8th Cir. 2006) (‘‘bulky’’ and valuable loads make the blind-mule defense less plausible)