United States v. Justin Davis, 2014 U.S. App. LEXIS 14400

Probation officer Warner observed suspicious short-term visitors to Apartment 5 and saw Justin Davis there; he summoned officer Gilson and drug-detection dog Bruno.
Gilson directed Bruno to sniff doorways from a common exterior walkway; Bruno alerted at Apartment 5 (nose at bottom of door and later inside doorway).
After Davis opened the door and encountered officers, Warner entered, detained Davis, then applied for a search warrant based on visitors and Bruno’s alerts; the warrant affidavit omitted the brief discovery of a scale and leafy material during the initial entry.
A state court issued the warrant; the subsequent search produced marijuana and cash. Davis moved to suppress, arguing the dog sniff was an unconstitutional search and tainted the warrant.
After briefing but before the district court ruled, the Supreme Court decided Florida v. Jardines (holding dog sniffs at a home are Fourth Amendment searches). The district court assumed Jardines invalidated the sniff but denied suppression under the good-faith exception.
The Eighth Circuit affirmed, assuming arguendo that the sniff violated the Fourth Amendment, but applying Davis v. United States to hold officers reasonably relied on binding Eighth Circuit precedent (United States v. Scott) so the exclusionary rule did not bar use of the sniff in the warrant application.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the warrantless dog sniff at Apartment 5 was a search that must be excluded and thus invalidate the warrant	Davis: Jardines makes the sniff unconstitutional and its fruits must be excluded from the warrant affidavit	Government: Officers relied on binding Eighth Circuit precedent (Scott) and thus acted reasonably before Jardines	Court: Assumed sniff was unconstitutional under Jardines but did not exclude its fruits because officers reasonably relied on then-binding precedent
Whether evidence from a search warrant based on a prior unconstitutional sniff must be excluded despite good-faith reliance on binding precedent	Davis: The Leon/affidavit-deletion approach should exclude derivative evidence obtained from a predicate illegal search	Government: Davis v. United States permits admission when officers acted in reasonable reliance on binding precedent authorizing the practice	Court: Applied Davis — exclusionary rule does not apply when officers reasonably relied on binding precedent, so warrant and search stand

Florida v. Jardines, 133 S. Ct. 1409 (2013) (dog-detection use at home is a Fourth Amendment search)
United States v. Leon, 468 U.S. 897 (1984) (good-faith exception to exclusionary rule for invalidated warrants)
Davis v. United States, 131 S. Ct. 2419 (2011) (evidence obtained in reasonable reliance on binding precedent is not subject to exclusionary rule)
United States v. Scott, 610 F.3d 1009 (8th Cir. 2010) (Eighth Circuit held a dog sniff of an apartment door from a common hallway was not a Fourth Amendment search)
United States v. Place, 462 U.S. 696 (1983) (dog-sniff precedent relied upon in lower courts)
United States v. Roby, 122 F.3d 1120 (8th Cir. 1997) (earlier Eighth Circuit dog-sniff decision relied on in Scott)