David Wayne Hatfield pled guilty to possession with intent to distribute marijuana in violation of 21 U.S.C. § 841(a)(1) and (b)(1)(D), and 18 U.S.C. § 2, and of maintaining a place for the purpose of manufacturing, distributing, and using methamphetamine and marijuana in violation of 21 U.S.C. §§ 856(a)(1) and 856(a)(2), and 18 U.S.C. § 2. He was sentenced by the United States District Court for the Eastern District of Oklahoma to imprisonment for thirty-six months. Before Hatfield entered his guilty plea, the district court had denied Hatfield’s motion to suppress evidence seized at his home pursuant to a warrant. As part of his plea agreement with the United States, Hatfield reserved the right to appeal that decision. In this appeal, Hatfield challenges the denial of the suppression motion, arguing that the evidence seized pursuant to the warrant was “fruit of the poisonous tree.” He claims that there were two poisonous trees in this case: two unconstitutional searches conducted prior to the issuance of the warrant that produced facts used by the police to obtain the warrant. Our jurisdiction arises under 28 U.S.C. § 1291, and we find that the police activity Hatfield complains of did not amount to searches triggering the protections of the Fourth Amendment. Accordingly, we AFFIRM the district court’s denial of Hatfield’s motion to suppress.
I
In the afternoon of October 10, 2000, the Sheriffs Department of Adair County, Oklahoma, received an anonymous tip that Hatfield was growing marijuana behind his house. Undersheriff Gary Sinclaire dispatched Lieutenant Tim McCullum and Deputy Linda Sinclaire to Hatfield’s home to conduct a “knock and talk” interview. The purpose of the interview was to inform Hatfield of the tip and ask his permission to search his property for marijuana.
Officers McCullum and Sinclaire arrived at Hatfield’s house at about 4:00 P.M. and parked their police car behind Hatfield’s pickup on the east side of the house on a concrete parking pad. When they got out of their car, Officer Sinclaire went to the front door on the north side of the house to make contact with Hatfield, and McCul-lum walked up the parking pad approximately twenty feet until he was alongside the passenger door of the pickup truck. *1191 McCullum did not leave the parking pad or enter the back yard, which lies to the south of the house. He took his position for protective purposes, in case someone exited the house from the rear and moved toward the front of the house via the parking pad. From his position on the parking pad, Officer McCullum could see into the back yard. As soon as McCullum heard that Hatfield had answered the door and was speaking-to Officer Sinclaire, McCul-lum left his position alongside the pickup truck and returned to the passenger side of the patrol car where he could observe Hatfield and Sinclaire.
Officer McCullum heard Sinclaire tell Hatfield about the phone call informing them that marijuana was growing on Hatfield’s property and ask him if he would give them permission to search the property. Hatfield refused to consent to a search and told the Officers that they could not search his property without a warrant. McCullum and Sinclaire told Hatfield they would get a warrant, returned to their patrol car, and backed out onto the county road. Once they were parked on the road, they notified their superior by radio what had transpired and he told them to wait there until he arrived.
Overhearing the conversation on the radio, Deputy Dale Harrold proceeded to Hatfield’s home and arrived at the scene next. Harrold conferred with Officers McCullum and Sinclaire on the county road. They told him that they had received a tip that marijuana was growing behind Hatfield’s house, that they had sought Hatfield’s consent to a search of the property, but that Hatfield had refused to give his consent to the search. Officer Harrold also testified at the suppression hearing that Officer McCullum had told him he had seen small structures in the backyard in which marijuana might be growing.
Officer Harrold had several years of experience and training as a marijuana spotter with the Oklahoma Bureau of Narcotics, and after he was apprized of the situation at Hatfield’s residence he walked west down the county road for approximately fifty or sixty feet alongside a fenced pasture to a point from which he could look behind Hatfield’s house. From his vantage point on the county road, Harrold could see a tin shed and what appeared to be a chicken coop in the back yard, and he reported to be able to see what appeared to be marijuana growing behind the tin shed and inside the chicken coop. Wanting to confirm what he had seen from the road before arresting Hatfield, Officer Harrold walked back east along the county road to the fence separating Hatfield’s yard from the pasture, crossed into the pasture, and walked south along the fence toward the back of Hatfield’s house. When he reached a point along the fence across from the structures behind Hatfield’s house, he confirmed that marijuana was growing there.
While Officer Harrold was walking along the pasture-side of the fence toward the back of the house, Hatfield, too, was walking toward the back of the house, but in his yard, on the other side of the fence. Hatfield was yelling expletives at Harrold and repeatedly told him that he was trespassing and to get off of his property. Once Harrold had sighted the marijuana from inside the pasture, however, he instructed Hatfield to walk back to where the other officers were standing on the county road and Hatfield complied. When he reached the officers, Harrold instructed them to place Hatfield under arrest for cultivation of marijuana. The officers then conducted a protective sweep through the house to be sure no one else was present. The sweep lasted no more than thirty to *1192 forty-five seconds and disclosed no one else on the premises.
After the officers secured the premises, Officer Harrold left to obtain a search warrant. Harrold swore out an affidavit in support of the issuance of a warrant in which he stated that the Sheriffs Office had received an anonymous tip that marijuana was growing at Hatfield’s residence and that he had personally seen “approximately 12 marijuana plants in plain view in the yard” at Hatfield’s residence. A warrant was issued to search the house and the structures behind the house, and Har-rold returned to Hatfield’s property to execute the warrant. During the ensuing search, the officers seized marijuana plants growing in the chicken coop and in other locations in the back yard. They also seized marijuana plants hung for drying in another of the structures behind the house and an ice chest containing sixty-nine marijuana starter plants.
After the Government filed an initial indictment, Hatfield was charged in a fifteen-count superseding indictment on January 18, 2001, that alleged various drug and firearm crimes. Hatfield moved to suppress the evidence gathered at the search of his home and property, arguing that the search violated his Fourth Amendment rights because (1) the search of his property was based upon an uncorroborated, anonymous tip; (2) the marijuana was growing in the curtilage of Hatfield’s home and Officer Harrold illegally trespassed on Hatfield’s property to see it; and (3) the protective sweep of Hatfield’s house had constituted an additional war-rantless search.
The district court held a suppression hearing at which several of the officers who participated in the events testified. After considering the record created by the hearing, the district court issued an ■order denying Hatfield’s suppression motion. The district court concluded first that the anonymous tip formed only the basis for the officer’s “knock and talk” interview, not the basis for obtaining a search warrant. Once Hatfield had refused consent to a search, the officers retreated to the county road in front of his house. The nature of the tip, the court concluded, therefore was irrelevant to the validity of the subsequent searches. Next, the court ruled that under the “open fields” doctrine Officer Harrold properly could have entered the pasture adjoining Hatfield’s property, and his sighting of the marijuana from the pasture was not an unreasonable search in violation of the Fourth Amendment. Finally, the district court concluded that, not only was the protective sweep proper, but that Hatfield’s objection to it was merely “academic” because the officers found no evidence during that sweep.
After his motion was denied, Hatfield entered into a plea agreement with the Government under which he pled guilty to one count of possession with intent to distribute marijuana in violation of 21 U.S.C. § 841(a)(1) and (b)(1)(D), and 18 U.S.C. § 2, and to one count of maintaining a place for the purpose of manufacturing, distributing, and using methamphetamine and marijuana in violation of 21 U.S.C. §§ 856(a)(1) and 856(a)(2), and 18 U.S.C. § 2. In exchange for this guilty plea, the Government agreed to drop the other counts in the indictment. The agreement also specifically reserved, pursuant to Fed.R.Crim.P. 11(a)(2), Hatfield’s right to appeal the district court’s denial of his motion to suppress. The district court accepted Hatfield’s plea and entered a judgment of conviction against him on November 13, 2001, in which the court sentenced Hatfield to two concurrent thirty-six month terms of imprisonment. Hatfield timely filed a notice of appeal to challenge *1193 the district court’s denial of his motion to suppress.
II
In reviewing the decision of a district court to deny a motion to suppress, “we accept its factual findings unless clearly erroneous and view the evidence in the light most favorable to the government.”
United States v. Le,
On appeal, Hatfield reframes the challenge he made below to the seizure of evidence at his home. He drops the arguments that the anonymous tip did not justify the knock and talk interview and that the protective sweep through his house constituted an impermissible, warrantless search. Instead, he builds upon his argument made to the district court that Har-rold conducted an unconstitutional search of the back yard while standing in the pasture. Before us Hatfield argues that the evidence seized pursuant to the warrant was “fruit of the poisonous tree” because the key fact cited in the affidavit to establish probable cause for the issuance of the search warrant — Officer Harrold’s statement that he saw marijuana in plain view in Hatfield’s back yard — was based upon two alleged unconstitutional searches. First, Hatfield says that Officer McCullum conducted an unconstitutional search of the back yard of his home during the knock and talk interview, and that his observations of the back yard directed Officer Harrold to examine the chicken coop where the marijuana was discovered during his subsequent search. Second, Hatfield argues that Harrold’s observation was an unconstitutional search because Officer Harrold trespassed into Hatfield’s adjacent pasture to see into the back yard and the chicken coop. Hatfield urges that because the warrant was issued based upon facts gleaned from these alleged unconstitutional searches, the evidence seized pursuant to the warrant was fruit of those poisonous trees and it should have been suppressed. 1
Under the fruit of the poisonous tree doctrine, the exclusionary rule bars the admission of physical evidence and live
*1194
testimony obtained directly or indirectly through the exploitation of unconstitutional police conduct.
Wong Sun v. United States,
A
Hatfield claims that McCullum, while standing within the curtilage of Hatfield’s home, conducted an unconstitutional search of the backyard during the knock and talk interview and passed on what he learned to Officer Harrold. Hatfield argues that he had a reasonable expectation of privacy in his backyard and McCullum’s inspection of it without a warrant constituted a search in violation of the Fourth Amendment. We find this argument unavailing.
Even if Officer- McCullum could have observed the marijuana growing in Hatfield’s back yard from his vantage point on the parking pad, it would not have amounted to an impermissible search. “[W]hen the police come on to private property to conduct an investigation ... and restrict their movements to places visitors could be expected to go (e.g., walkways, driveways, porches), observations made from such vantage points are not covered by the Fourth Amendment.” 1 Wayne R. LaFave,
Search & Seizure: A Treatise on the Fourth Amendment
§ 2.3(f), at 506-08 (3d ed.1996) (footnotes omitted);
see also United States v. Reyes,
In the instant case, Hatfield’s driveway was open to the public, permitting the Officers to park their patrol car directly behind Hatfield’s pickup. The openness and accessibility of a driveway to the public has been an important factor that courts have used to conclude that an owner does not have a reasonable expectation of privacy and that police observations made from the driveway do not constitute a search.
See, e.g., Reyes,
B
We turn next to Hatfield’s contention that Officer Harrold’s inspection of Hatfield’s back yard from the pasture was an unconstitutional search. He argues that the “open fields” doctrine does not apply to the pasture adjacent to his yard and, accordingly, Officer Harrold’s presence in the field without a warrant violated the Fourth Amendment. We disagree that Officer Harrold’s observation of the marijuana constituted an unconstitutional search.
“The touchstone of Fourth Amendment analysis is whether a person has a ‘constitutionally protected reasonable expectation of privacy.’ ”
California v. Cirao-lo,
The “prototypical ... area of protected privacy” is the interior of a home.
Kyllo v. United States,
In this case, the location of the marijuana observed by Officer Harrold was in a well-defined yard behind Hatfield’s residence, in and among several small structures standing close to the back of the house. The area could not be observed clearly from the street, as illustrated by the fact that Officer Harrold was not certain that he had seen marijuana when he looked into the backyard from a position west of the house on the county road. We hold that the marijuana was located in the curtilage of Hatfield’s home because “the area in question is so intimately tied to the home itself that it should be placed under the home’s ‘umbrella’ of Fourth Amendment protection .”
United States v. Dunn,
Although privacy in the interior of a home and its curtilage. are at the core of what the Fourth Amendment protects, there is no reasonable expectation that a home and its curtilage will be free from ordinary visual surveillance. “The Fourth Amendment protection of the home has never been extended to require law enforcement officers to shield their eyes when passing by a home on public thoroughfares.”
Ciraolo,
*1197
In the instant case, of course, Officer Harrold was not standing on a neighbor’s property or on a public thoroughfare when he saw the marijuana in Hatfield’s yard. The observation was made from Hatfield’s own pasture, and Hatfield makes much of the fact that Officer Harrold was trespassing in the pasture and in Oklahoma trespassing is a crime. The crux of the issue before us, then, is whether the fact that the pasture was owned by Hatfield himself, and that persons in the field are trespassers, created a reasonable expectation of privacy from observations of Hatfield’s curtilage made from the pasture. We conclude that the Supreme Court’s decision in
Dunn
and our decision in
Fullbright v. United States,
In
Dunn,
the Court upheld a search by two trespassing officers in which they stood on the defendant’s property outside of a barn, looked in through an open space in the main doorway of the barn, and discovered drug paraphernalia.
The Court then addressed the question of whether it was a Fourth Amendment violation for the officers, while standing in an open field, to search the interior space of the barn by looking into it. Assuming, but not deciding, that the interior space of the barn was protected by the Fourth Amendment,
id.
at 303,
Furthermore, the Court said that, “the fact that the objects observed by the officers lay within an area that we have assumed ... was protected by the Fourth Amendment does not affect our conclusion.” Id. The Court emphasized that “the officers never entered the barn, nor did they enter any other structure on respondent’s premises.” Id. Instead, “[o]nce at their vantage point, they merely stood, outside the curtilage of the house and in the open fields upon which the barn was constructed, and peered into ■ the barn’s open front.” Id. Thus, “standing as they were in the open fields, the Constitution did not forbid them to observe the [drug] laboratory located in respondent’s barn.” Id.
Similarly,
Fullbright
involved law enforcement officers who, while trespassing on the defendant’s open fields, observed from a distance the interior of an open shed located in the property’s curtilage.
Following
Dunn
and
Fullbright,
we hold that police observation of a defendant’s curtilage from a vantage point in the defendant’s open field is not a search under the Fourth Amendment. Even though we can conclude that Hatfield had a subjective expectation of privacy in the space immediately behind his house, this is not an expectation of privacy that society regards as reasonable, at least with respect to visual observations made from an adjoining open field. Had Officer Harrold physically invaded the curtilage to make his observation, that would have constituted a search subject to the proscriptions of the Fourth Amendment.
See Dunn,
Hatfield relies heavily on the fact that Officer Harrold’s presence in the pasture violated Oklahoma’s criminal trespass statute. This fact does not, however, change our analysis. The Oklahoma criminal trespass statute to which Hatfield points, Okla. Stat. Ann. tit. 21, § 1835 (West 2000), has been on the books in one form or another since 1913.
See id.
(Historical and Statutory Notes). Despite the law’s longevity, we have never found it to be relevant to Fourth Amendment analysis of whether an officer was properly in an open field in cases arising in Oklahoma. For example, the relevant provision of the statute that was in force during the events of the instant case was also in force in 1993 when we decided
Pinter.
In
Pinter,
two DEA agents trespassed onto the defendant’s oil lease in Oklahoma while surveilling him.
For the foregoing reasons, we conclude that Hatfield did not have a constitutionally protected privacy interest in being free from police observations of his curtilage made from his adjoining pasture. Officer Harrold’s sighting of the marijuana in Hatfield’s back yard therefore did not constitute a Fourth Amendment search.
Ill
We hold that neither the actions of Officer McCullum nor the actions of Officer Harrold constituted an impermissible search. Accordingly, the affidavit supporting the search warrant did not contain tainted factual allegations, and the evidence seized pursuant to the warrant was not fruit of a poisonous tree. We therefore AFFIRM the district court’s decision denying the motion to suppress.
Notes
. Hatfield also briefly raises the argument that the warrant was defective because it was issued without probable cause. Hatfield fails to fully develop this argument, and, in any event, it has no merit. The facts in Officer Harrold’s affidavit are undisputed: an anonymous informant told the Sheriff’s Office that Hatfield was growing marijuana behind his house and Officer Harrold personally observed the marijuana. "A magistrate's determination that probable cause exists is entitled to 'great deference,’ and 'we ask only whether the issuing magistrate had a 'substantial basis’ for determining probable cause existed.’ ”
Le,
. We note, furthermore, that the record is clear that Officer McCullum did not see any marijuana from his vantage point on the driveway. At most, he might have seen the chicken coop in the back yard. We do not see, therefore, how any observations made by Officer McCullum would have influenced Officer Harrold’s later decision to investigate the back yard himself from the adjoining pasture and have tainted Harrold’s observation. Hatfield suggests that Officer Harrold would not have inspected the chicken coop if Officer McCullum had not told him about it. But Harrold knew that the anonymous tip had specifically indicated that the marijuana was in Hatfield’s back yard. Harrold knew, because the anonymous tip directed the officers to the back yard, that if he were to look for marijuana he would look behind the house.
. "[T]he term 'open fields’ may include any unoccupied or undeveloped area outside of the curtilage. An open field need be neither 'open' nor a 'field' as those terms are used in common speech.”
Oliver,
. We note, however, that some police observations made from an open field could constitute an unconstitutional search. For example, in
Kyllo,
the Supreme Court held that "obtaining by sense-enhancing technology any information regarding the interior of the home that could not otherwise have been obtained without physical intrusion into a constitutionally protected area constitutes a search — at least where (as here) the technology in question is not in general public use.”