United States v. Pennington
United States Court of Appeals for the Fifth Circuit
20 F.3d 593 (1994)
John Wayne Pennington and John Mitchell Margiotta (defendants), novice truckers, were stopped for an overweight truck, and a drug-sniffing dog found 591 pounds of marijuana hidden behind legitimate tile cargo; the truckers hadn't loaded the cargo themselves, left the truck unlocked overnight, and did not appear nervous, flee, or carry suspicious amounts of cash, though they struggled to explain why they were behind schedule and taking an unusual route. The jury convicted both men of possession with intent to distribute, and they appealed.
Whether the presence of illegal drugs in a defendant's vehicle is enough, by itself, to prove the defendant knew the drugs were there and thus establish the knowledge element of possession with intent to distribute.