United States Court of Appeals
                             For the Eighth Circuit
                         ___________________________

                                 No. 13-2285
                         ___________________________

                              United States of America

                        lllllllllllllllllllll Plaintiff - Appellee

                                           v.

                                     Justin Davis

                       lllllllllllllllllllll Defendant - Appellant
                                       ____________

                     Appeal from United States District Court
                 for the Northern District of Iowa - Cedar Rapids
                                  ____________

                             Submitted: April 16, 2014
                               Filed: July 29, 2014
                                 ____________

Before LOKEN and MURPHY, Circuit Judges, and LIMBAUGH,* District Judge.
                          ____________

LOKEN, Circuit Judge.

       Justin Davis entered a conditional plea of guilty to possessing marijuana with
intent to distribute after his motion to suppress evidence found during a warrant
search of his apartment was denied. The search warrant application was based in part


      *
       The Honorable Stephen N. Limbaugh, Jr., United States District Judge for the
Eastern District of Missouri, sitting by designation.
on a drug-detection dog’s sniff outside the apartment’s front door. After the motion
to suppress was briefed and argued, but before the court ruled, the Supreme Court
issued its decision in Florida v. Jardines, holding that “[t]he government’s use of
trained police dogs to investigate the home and its immediate surroundings is a
‘search’ within the meaning of the Fourth Amendment.” 

, 1417-18
(2013). The district court1 assumed that Jardines invalidated the dog sniff and
therefore the search warrant but nonetheless denied the motion to suppress,
concluding that “the Leon good-faith exception applies”2 because the officers
executing the warrant “could have reasonably believed that the dog sniff at the door
to Apartment 5 was lawful in light of the Eighth Circuit’s decision in United States
v. Scott, 

(8th Cir. 2010),” cert. denied, 

(2011). Davis
appeals the denial of his motion to suppress. Reviewing Fourth Amendment issues
de novo, we affirm. See United States v. Cannon, 

, 412 (8th Cir.)
(standard of review), cert. denied, 

(2013).

                                         I.

      In 2012, Davis was serving a term of probation following an Iowa state court
drug conviction. On December 12, Cedar Rapids police advised Probation Officer
Steve Warner that a black Buick Riviera associated with Davis had been seen at the
Cambridge Apartment Complex. Warner located the Riviera parked next to a
building in the complex and positioned his unmarked vehicle to watch the area. Over

      1
      The Honorable Linda R. Reade, Chief Judge, United States District Court for
the Northern District of Iowa, adopting in part the Report and Recommendation of
the Honorable Jon S. Scoles, Chief Magistrate Judge, United States District Court for
the Northern District of Iowa.
      2
       United States v. Leon, 

, 922 (1984), held that, with certain
exceptions, the Fourth Amendment’s exclusionary rule does not require suppression
of “evidence obtained in objectively reasonable reliance on a subsequently
invalidated search warrant.”

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the course of an hour, Warner saw three men enter and quickly leave Apartment 5,
where the Riviera was parked, and he saw Davis exit Apartment 5 and approach a red
car parked next to the Riviera, which then quickly left. Suspecting on-going drug
transactions, Warner called Officer Jeff Gilson, a local police canine handler, and
asked him to bring his drug-detection dog, Bruno, to the building. While waiting for
Gilson, Warner saw Davis meet a woman in the building’s yard and escort her into
Apartment 5; she left less than a minute later.

      Gilson arrived, wearing plain clothes and escorting Bruno. At Warner’s
request, Gilson instructed Bruno to sniff outside each apartment door, starting at the
south end of the building. The building had four doors opening directly into the
apartments. The third door from the south end was Apartment 5; a few inches away
was the door to the next apartment, with two mailboxes mounted one above the other
on the wall between the two doors. A single sidewalk ran from the parking area to
both doors. Bruno detected no drug odors until he reached Apartment 5, where he
snorted and assumed a “locked position,” with his nose touching the bottom of the
door. Bruno moved to the last door and quickly returned to Apartment 5, where he
again alerted. Davis opened the door and asked Gilson what he was doing. While
Davis and Gilson chatted, Bruno attempted to enter the apartment and then sat in the
corner of the doorway, again indicating he detected the scent of narcotics. Davis
closed the door. Gilson and Bruno met with Warner.

       Concerned that Davis had recognized a police dog and would destroy evidence
of drug trafficking, Warner and two police officers knocked on the door to Apartment
5. Erica Lewis answered, cracking open the door, which allowed Warner to see Davis
sitting on a couch in the room. Warner entered the apartment and placed Davis in
custody. The officers discovered a scale and “green leafy substance” on the kitchen
table while checking the apartment for other occupants. With the apartment secured,
Warner left to apply for a search warrant. In his supporting affidavit, Warner
recounted the string of visitors to the apartment, the events surrounding Bruno’s

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alerts, and the events following Warner’s knock on the door, but not the discovery of
the scale and green leafy substance. The state court issued the search warrant. The
officers promptly searched Apartment 5 and seized marijuana and cash.

       Davis moved to suppress this evidence, arguing the dog sniff at his apartment
door without a warrant violated the Fourth Amendment and therefore could not be
used to establish probable cause, invalidating the warrant and the subsequent warrant
search of his apartment. On February 5, 2013, Magistrate Judge Scoles recommended
that Davis’s motion be denied for three reasons. First, the dog sniff was not a search
subject to the Fourth Amendment, an issue “governed” by our decision in Scott and
then-existing Supreme Court precedent. Second, even if the dog sniff was excluded,
the warrant affidavit reciting a series of short-term visitors to Apartment 5 sufficiently
supported the finding of probable cause to issue the warrant. Third, even if the
warrant was not valid, the officers executed the warrant in good faith, so evidence
found during the warrant search should not be excluded under Leon.

      On March 4, Davis entered a conditional guilty plea, reserving the right to
pursue his suppression motion in the district court and on appeal. On March 26, the
Supreme Court issued its decision in Jardines. On April 16, the district court denied
the motion to suppress, concluding only that the good faith exception applied. Like
the district court, we will consider only the good faith issue, assuming without
deciding that the warrantless dog sniff outside the door to Apartment 5 violated
Davis’s Fourth Amendment rights as construed in Jardines.

                                           II.

       “A violation of the Fourth Amendment usually triggers exclusion of evidence
‘obtained by way of’ the violation from a subsequent criminal prosecution.” United
States v. Barraza-Maldonado, 

, 867 (8th Cir. 2013), quoting Davis v.
United States, 

, 2423 (2011). “The exclusionary rule prohibits

                                           -4-
introduction into evidence of tangible materials seized during an unlawful search . . . .
Beyond that, the exclusionary rule also prohibits the introduction of derivative
evidence . . . that is otherwise acquired as an indirect result of the unlawful search.”
Murray v. United States, 

, 536-37 (1988).

       Applying the exclusionary rule, we have held in many cases that “[t]he
sufficiency of a warrant affidavit which contains information from an unlawful search
is evaluated after deleting that information.” United States v. Hernandez Leon, 

, 1027 (8th Cir. 2004), and cases cited. But we have also applied the Leon
good faith exception when the warrant was based on evidence obtained through a
Fourth Amendment violation if “the detectives’ prewarrant conduct [was] close
enough to the line of validity to make the officers’ belief in the validity of the warrant
objectively reasonable.” 

(quotation omitted). The district
court applied the rule in Cannon because, at the time of the dog sniff, the officers
could reasonably rely on our decision in Scott as establishing that no warrant to
conduct a sniff outside the apartment was required.

       On appeal, Davis argues that suppression of evidence found in executing an
invalid warrant cannot be denied under the Leon good faith doctrine when the
invalidity results from a “predicate illegal search,” here, a dog sniff violating his
constitutional rights under Jardines. Therefore, he argues, the district court should
have applied the affidavit-deletion rule in Hernandez Leon or, alternatively, should
have concluded that the officers’ “aggressive” use of the controversial dog sniff
procedure was not “close enough to the line” to warrant the Leon good faith
exception under Cannon. We conclude that we need not resolve those issues, which
relate to the proper scope of the Leon exception, because this case is governed by the
distinct exception to the exclusionary rule in Davis.

     In Davis, the Supreme Court held that “[e]vidence obtained during a search
conducted in reasonable reliance on binding precedent is not subject to the

                                           -5-
exclusionary 

(emphasis added). When an otherwise valid
search warrant is based upon evidence obtained in a prior warrantless search that
violated the Fourth Amendment, it is the exclusionary rule that prohibits use of this
derivative evidence to establish the probable cause needed to obtain a valid warrant.
See 

(“suppression of evidence obtained pursuant to a warrant
should be ordered . . . only [when] exclusion will further the purposes of the
exclusionary rule”); Segura v. United States, 

, 813-15 (1984). Thus, if
the evidence uncovered by Bruno’s sniff was not subject to the exclusionary rule
under Davis, then it was properly used to obtain a valid warrant, and there was no
basis to suppress evidence seized during the subsequent warrant search.

       Prior to Officer Gilson instructing Bruno to sniff for narcotics outside the door
to Apartment 5 at Probation Officer Warner’s request, we held that a drug-detection
dog’s “sniff of the apartment door frame from a common hallway did not constitute
a search subject to the Fourth Amendment.” 

. Here, Bruno
sniffed Apartment 5’s door frame from a common walkway. Magistrate Judge Scoles
ruled, before the Supreme Court decided Jardines, that our decision in Scott
“governed” whether Bruno’s sniff was a search subject to the Fourth Amendment.
This confirms that the officers acted in objectively reasonable reliance on binding
appellate precedent in conducting a warrantless dog sniff outside the apartment door.

       Davis argues that the good faith exception in Davis should not apply to the dog
sniff because Scott was not longstanding precedent at the time of the search and dog
sniffs of residences were not routine law enforcement practices, unlike the officers’
reliance on longstanding Eleventh Circuit precedent in 

.
The premise of the argument is unsound, because our Fourth Amendment analysis in
Scott was well-grounded in a prior dog-sniff decision of this court, United States v.
Roby, 

, 1124-25 (8th Cir. 1997), and in the Supreme Court’s dog-sniff
decision in United States v. Place, 

(1983), on which Roby relied.
Moreover, nothing in the majority opinion in Davis suggested that its good faith

                                          -6-
exception is limited to longstanding judicial precedent or to routine law enforcement
practices. “[W]hen binding appellate precedent specifically authorizes a particular
police practice,” the Court explained, “well-trained officers will and should use that
tool to fulfill their crime-detection and public-safety responsibilities.” Davis, 131 S.
Ct. at 2429 (emphasis in original). Applying the exclusionary rule in these
circumstances would “penalize the officer for the appellate judges’ error.” 

argues that the officers could not have reasonably relied on Scott
because the Supreme Court had heard argument in Jardines, casting doubt on Scott’s
vitality. We rejected that argument in Barraza-Maldonado, concluding that officers
reasonably relied on binding circuit precedent when, without a warrant, they installed
a GPS device to monitor the movements of a car prior to the Supreme Court’s
decision in United States v. Jones, 

(2012). “Officers should not be
faulted for adhering to existing precedent until that precedent is authoritatively
overruled,” we explained. 

. “When the police
comply with authoritative precedent, only to see the law evolve after the fact, there
is nothing to deter; the police cannot modify their conduct to accord with cases not
yet decided.” 

States v. Sparks, 

, 63 (1st Cir.), cert.
denied, 

(2013). The same is true in this case. Scott had not been
“authoritatively overruled” at the time of the dog sniff in question.

      Because the officers reasonably relied on binding circuit precedent in
conducting a dog sniff outside the door to Apartment 5, the exclusionary rule did not
apply to preclude use of that evidence in the search warrant application. Therefore,
the warrant was valid, and Davis’s motion to suppress was properly denied.

      The judgment of the district court is affirmed.
                     ______________________________




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