# United States v. Knotts, 460 U.S. 276 (1983) > *Archived legal-authority source. The public original was independently acquired and preserved on 2026-08-10.* ## Source metadata - **Publisher or court:** United States Supreme Court - **URL:** https://www.govinfo.gov/content/pkg/USREPORTS-460/pdf/USREPORTS-460-276.pdf - **Resolved URL:** https://www.govinfo.gov/content/pkg/USREPORTS-460/pdf/USREPORTS-460-276.pdf - **Archived:** 2026-08-10, from unauthenticated public access - **Wayback snapshot:** save failed 2026-08-10; retry pending - **Source class:** primary public record or court opinion ## Proposition boundary A single public-road beeper journey was not a search. The Court expressly reserved dragnet-type surveillance and private-place monitoring. ## Extract ### Page 1 276 OCTOBER TERM, 1982 Syllabus 460 U. S. UNITED STATES v. KNOTTS CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE EIGHTH CIRCUIT No. 81-1802. Argued December 6 1982—Decided March 2, 1983 Having reason to believe that one Armstrong was purchasing chloroform to be used in the manufacture of illicit drugs, Minnesota law enforcement officers arranged with the seller to place a beeper (a radio transmitter) inside a chloroform container that was sold to Armstrong. Officers then followed the car in which the chloroform was placed, maintaining contact by using both visual surveillance and a monitor which received the beeper signals, and ultimately tracing the chloroform, by beeper moni- toring alone, to respondent’s secluded cabin in Wisconsin. Following three days of intermittent visual surveillance of the cabin, officers se- cured a search warrant and discovered the chloroform container, and a drug laboratory in the cabin, including chemicals and formulas for pro- ducing amphetamine. After his motion to suppress evidence based on the warrantless monitoring of the beeper was denied, respondent was convicted in Federal District Court for conspiring to manufacture con- trolled substances in violation of 21 U. S. C. § 846. The Court of Ap- peals reversed, holding that the monitoring of the beeper was prohibited by the Fourth Amendment. Held: Monitoring the beeper signals did not invade any legitimate expecta- tion of privacy on respondent’s part, and thus there was neither a “search” nor a “seizure” within the contemplation of the Fourth Amend- ment. The beeper surveillance amounted principally to following an automobile on public streets and highways. A person traveling in an automobile on public thoroughfares has no reasonable expectation of pri- vacy in his movements. While respondent had the traditional expecta- tion of privacy within a dwelling place insofar as his cabin was concerned, such expectation of privacy would not have extended to the visual ob- servation from public places of the automobile arriving on his premises after leaving a public highway, or to movements of objects such as the chloroform container outside the cabin. The fact that the officers relied not only on visual surveillance, but also on the use of the beeper, does not alter the situation. Nothing in the Fourth Amendment prohibited the police from augmenting their sensory faculties with such enhance- ment as science and technology afforded them in this case. There is no indication that the beeper was used in any way to reveal information as to the movement of the chloroform container within the cabin, or in any ### Page 2 UNITED STATES v. KNOTTS 277 276 Opinion of the Court way that would not have been visible to the naked eye from outside the cabin. Pp. 280-285. 662 F. 2d 515, reversed. Rehn qu ist , J., delivered the opinion of the Court, in which Burg er , C. J., and Whi te , Powel l , and O’Conno r , JJ., joined. Bren na n , J., filed an opinion concurring in the judgment, in which Mars ha ll , J., joined, post, p. 285. Blackmu n , J., filed an opinion concurring in the judgment, in which Bren na n , Mars hal l , and Ste ve ns , JJ., joined, post, p. 287. Ste ven s , J., filed an opinion concurring in the judgment, in which Brenna n , and Marsh al l , JJ., joined, post, p. 288. Deputy Solicitor General Frey argued the cause for the United States. With him on the briefs were Solicitor General Lee, Assistant Attorney General Jensen, Elliott Schulder, and Gloria C. Phares. Mark W. Peterson argued the cause and filed a brief for respondent. Justi ce Rehnquis t delivered the opinion of the Court. A beeper is a radio transmitter, usually battery operated, which emits periodic signals that can be picked up by a radio receiver. In this case, a beeper was placed in a five-gallon drum containing chloroform purchased by one of respondent’s codefendants. By monitoring the progress of a car carrying the chloroform Minnesota law enforcement agents were able to trace the can of chloroform from its place of purchase in Minneapolis, Minn., to respondent’s secluded cabin near Shell Lake, Wis. The issue presented by the case is whether such use of a beeper violated respondent’s rights secured by the Fourth Amendment to the United States Constitution. I Respondent and two codefendants were charged in the United States District Court for the District of Minnesota with conspiracy to manufacture controlled substances, in- cluding but not limited to methamphetamine, in violation of 21 U. S. C. § 846. One of the codefendants, Darryl Petschen, ### Page 3 278 OCTOBER TERM, 1982 Opinion of the Court 460 U. S. was tried jointly with respondent; the other codefendant, Tristan Armstrong, pleaded guilty and testified for the Gov- ernment at trial. Suspicion attached to this trio when the 3M Co., which manufactures chemicals in St. Paul, notified a narcotics in- vestigator for the Minnesota Bureau of Criminal Apprehen- sion that Armstrong, a former 3M employee, had been steal- ing chemicals which could be used in manufacturing illicit drugs. Visual surveillance of Armstrong revealed that after leaving the employ of 3M Co., he had been purchasing similar chemicals from the Hawkins Chemical Co. in Minneapolis. The Minnesota narcotics officers observed that after Arm- strong had made a purchase, he would deliver the chemicals to codefendant Petschen. With the consent of the Hawkins Chemical Co., officers installed a beeper inside a five-gallon container of chloro- form, one of the so-called “precursor” chemicals used to manufacture illicit drugs. Hawkins agreed that when Arm- strong next purchased chloroform, the chloroform would be placed in this particular container. When Armstrong made the purchase, officers followed the car in which the chloro- form had been placed, maintaining contact by using both vis- ual surveillance and a monitor which received the signals sent from the beeper. Armstrong proceeded to Petschen’s house, where the con- tainer was transferred to Petschen’s automobile. Officers then followed that vehicle eastward towards the state line, across the St. Croix River, and into Wisconsin. During the latter part of this journey, Petschen began making evasive maneuvers, and the pursuing agents ended their visual sur- veillance. At about the same time officers lost the signal from the beeper, but with the assistance of a monitoring de- vice located in a helicopter the approximate location of the signal was picked up again about one hour later. The signal now was stationary and the location identified was a cabin occupied by respondent near Shell Lake, Wis. The record before us does not reveal that the beeper was used after the ### Page 4 UNITED STATES v. KNOTTS 279 276 Opinion of the Court location in the area of the cabin had been initially determined. Relying on the location of the chloroform derived through the use of the beeper and additional information obtained during three days of intermittent visual surveillance of re- spondent’s cabin, officers secured a search warrant. During execution of the warrant, officers discovered a fully operable, clandestine drug laboratory in the cabin. In the laboratory area officers found formulas for amphetamine and metham- phetamine, over $10,000 worth of laboratory equipment, and chemicals in quantities sufficient to produce 14 pounds of pure amphetamine. Under a barrel outside the cabin, offi- cers located the five-gallon container of chloroform. After his motion to suppress evidence based on the war- rantless monitoring of the beeper was denied, respondent was convicted for conspiring to manufacture controlled sub- stances in violation of 21 U. S. C. §846. He was sentenced to five years’ imprisonment. A divided panel of the United States Court of Appeals for the Eighth Circuit reversed the conviction, finding that the monitoring of the beeper was pro- hibited by the Fourth Amendment because its use had vio- lated respondent’s reasonable expectation of privacy, and that all information derived after the location of the cabin was a fruit of the illegal beeper monitoring. * 662 F. 2d 515 *Respondent does not challenge the warrantless installation of the beeper in the chloroform container, suggesting in oral argument that he did not believe he had standing to make such a challenge. We note that while several Courts of Appeals have approved warrantless installations, see United States v. Bernard, 625 F. 2d 854 (CA9 1980); United States v. Lewis, 621 F. 2d 1382 (CA5 1980), cert, denied, 450 U. S. 935 (1981); United States v. Bruneau, 594 F. 2d 1190 (CA8), cert, denied, 444 U. S. 847 (1979); United States v. Miroyan, 577 F. 2d 489 (CA9), cert, denied, 439 U. S. 896 (1978); United States v. Cheshire, 569 F. 2d 887 (CA5), cert, denied, 437 U. S. 907 (1978); United States v. Curtis, 562 F. 2d 1153 (CA9 1977), cert, denied, 439 U. S. 910 (1978); United States v. Abel, 548 F. 2d 591 (CA5), cert, denied, 431 U. S. 956 (1977); United States v. Hufford, 539 F. 2d 32 (CA9), cert, denied, 429 U. S. 1002 (1976), we have not before and do not now pass on the issue. ### Page 5 280 OCTOBER TERM, 1982 Opinion of the Court 460 U. S. (1981). We granted certiorari, 457 U. S. 1131 (1982), and we now reverse the judgment of the Court of Appeals. II In Olmstead v. United States, 277 U. S. 438 (1928), this Court held that the wiretapping of a defendant’s private tele- phone line did not violate the Fourth Amendment because the wiretapping had been effectuated without a physical tres- pass by the Government. Justice Brandeis, joined by Jus- tice Stone, dissented from that decision, believing that the actions of the Government in that case constituted an “unjus- tifiable intrusion . . . upon the privacy of the individual,” and therefore a violation of the Fourth Amendment. Id., at 478. Nearly 40 years later, in Katz v. United States, 389 U. S. 347 (1967), the Court overruled Olmstead saying that the Fourth Amendment’s reach “cannot turn upon the presence or ab- sence of a physical intrusion into any given enclosure.” 389 U. S., at 353. The Court said: “The Government’s activities in electronically listening to and recording the petitioner’s words violated the pri- vacy upon which he justifiably relied while using the telephone booth and thus constituted a ‘search and sei- zure’ within the meaning of the Fourth Amendment. The fact that the electronic device employed to achieve that end did not happen to penetrate the wall of the booth can have no constitutional significance.” Ibid. In Smith v. Maryland, 442 U. S. 735 (1979), we elaborated on the principles stated in Katz: “Consistently with Katz, this Court uniformly has held that the application of the Fourth Amendment depends on whether the person invoking its protection can claim a ‘justifiable,’ a ‘reasonable,’ or a ‘legitimate expectation of privacy’ that has been invaded by government action. [Citations omitted.] This inquiry, as Mr. Justice Harlan aptly noted in his Katz concurrence, normally embraces ### Page 6 UNITED STATES v. KNOTTS 281 276 Opinion of the Court two discrete questions. The first is whether the individ- ual, by his conduct, has ‘exhibited an actual (subjective) expectation of privacy,’ 389 U. S., at 361—whether, in the words of the Katz majority, the individual has shown that ‘he seeks to preserve [something] as private.’ Id., at 351. The second question is whether the individual’s subjective expectation of privacy is ‘one that society is prepared to recognize as “reasonable,”’ id., at 361— whether, in the words of the Katz majority, the indi- vidual’s expectation, viewed objectively, is ‘justifiable’ under the circumstances. Id., at 353. See Rakas v. Il- linois, 439 U. S., at 143-144, n. 12; id., at 151 (concur- ring opinion); United States v. White, 401 U. S., at 752 (plurality opinion).” 442 U. S., at 740-741 (footnote omitted). The governmental surveillance conducted by means of the beeper in this case amounted principally to the following of an automobile on public streets and highways. We have com- mented more than once on the diminished expectation of pri- vacy in an automobile: “One has a lesser expectation of privacy in a motor vehi- cle because its function is transportation and it seldom serves as one’s residence or as the repository of personal effects. A car has little capacity for escaping public scrutiny. It travels public thoroughfares where both its occupants and its contents are in plain view.” Cardwell v. Lewis, 417 U. S. 583, 590 (1974) (plurality opinion). See also Rakas v. Illinois, 439 U. S. 128, 153-154, and n. 2 (1978) (Powell , J., concurring); South Dakota v. Opperman, 428 U. S. 364, 368 (1976). A person traveling in an automobile on public thorough- fares has no reasonable expectation of privacy in his move- ments from one place to another. When Petschen traveled over the public streets he voluntarily conveyed to anyone who wanted to look the fact that he was traveling over par- ### Page 7 282 OCTOBER TERM, 1982 Opinion of the Court 460 U. S. ticular roads in a particular direction, the fact of whatever stops he made, and the fact of his final destination when he exited from public roads onto private property. Respondent Knotts, as the owner of the cabin and sur- rounding premises to which Petschen drove, undoubtedly had the traditional expectation of privacy within a dwelling place insofar as the cabin was concerned: “Crime, even in the privacy of one’s own quarters, is, of course, of grave concern to society, and the law allows such crime to be reached on proper showing. The right of officers to thrust themselves into a home is also of grave concern, not only to the individual, but to a society which chooses to dwell in reasonable security and free- dom from surveillance. When the right of privacy must reasonably yield to the right of search is, as a rule, to be decided by a judicial officer, not by a policeman or government enforcement agent.” Johnson v. United States, 333 U. S. 10, 14 (1948), quoted with approval in Payton v. New York, 445 U. S. 573, 586 (1980). But no such expectation of privacy extended to the visual ob- servation of Petschen’s automobile arriving on his premises after leaving a public highway, nor to movements of objects such as the drum of chloroform outside the cabin in the “open fields.” Hester v. United States, 265 U. S. 57 (1924). Visual surveillance from public places along Petschen’s route or adjoining Knotts’ premises would have sufficed to reveal all of these facts to the police. The fact that the offi- cers in this case relied not only on visual surveillance, but also on the use of the beeper to signal the presence of Petschen’s automobile to the police receiver, does not alter the situation. Nothing in the Fourth Amendment prohibited the police from augmenting the sensory faculties bestowed upon them at birth with such enhancement as science and technology afforded them in this case. In United States v. Lee, 274 U. S. 559 (1927), the Court said: ### Page 8 UNITED STATES v. KNOTTS 283 276 Opinion of the Court “But no search on the high seas is shown. The testi- mony of the boatswain shows that he used a searchlight. It is not shown that there was any exploration below decks or under hatches. For aught that appears, the cases of liquor were on deck and, like the defendants, were discovered before the motor boat was boarded. Such use of a searchlight is comparable to the use of a marine glass or a field glass. It is not prohibited by the Constitution.” Id., at 563. We have recently had occasion to deal with another claim which was to some extent a factual counterpart of respond- ent’s assertions here. In Smith v. Maryland, we said: “This analysis dictates that [Smith] can claim no legiti- mate expectation of privacy here. When he used his phone, [Smith] voluntarily conveyed numerical informa- tion to the telephone company and ‘exposed’ that in- formation to its equipment in the ordinary course of busi- ness. In so doing, [Smith] assumed the risk that the company would reveal to police the numbers he dialed. The switching equipment that processed those numbers is merely the modem counterpart of the operator who, in an earlier day, personally completed calls for the sub- scriber. [Smith] concedes that if he had placed his calls through an operator, he could claim no legitimate expec- tation of privacy. [Citation omitted.] We are not in- clined to hold that a different constitutional result is re- quired because the telephone company has decided to automate.” 442 U. S., at 744-745. Respondent does not actually quarrel with this analysis, though he expresses the generalized view that the result of the holding sought by the Government would be that “twenty-four hour surveillance of any citizen of this country will be possible, without judicial knowledge or supervision.” Brief for Respondent 9 (footnote omitted). But the fact is that the “reality hardly suggests abuse,” Zurcher v. Stanford ### Page 9 284 OCTOBER TERM, 1982 Opinion of the Court 460 U. S. Daily, 436 U. S. 547, 566 (1978); if such dragnet-type law en- forcement practices as respondent envisions should eventu- ally occur, there will be time enough then to determine whether different constitutional principles may be applicable. Ibid. Insofar as respondent’s complaint appears to be sim- ply that scientific devices such as the beeper enabled the po- lice to be more effective in detecting crime, it simply has no constitutional foundation. We have never equated police efficiency with unconstitutionality, and we decline to do so now. Respondent specifically attacks the use of the beeper inso- far as it was used to determine that the can of chloroform had come to rest on his property at Shell Lake, Wis. He repeat- edly challenges the “use of the beeper to determine the loca- tion of the chemical drum at Respondent’s premises,” Brief for Respondent 26; he states that “[t]he government thus overlooks the fact that this case involves the sanctity of Re- spondent’s residence, which is accorded the greatest protec- tion available under the Fourth Amendment.” Ibid. The Court of Appeals appears to have rested its decision on this ground: “As noted above, a principal rationale for allowing war- rantless tracking of beepers, particularly beepers in or on an auto, is that beepers are merely a more effective means of observing what is already public. But people pass daily from public to private spheres. When police agents track bugged personal property without first ob- taining a warrant, they must do so at the risk that this enhanced surveillance, intrusive at best, might push for- tuitously and unreasonably into the private sphere pro- tected by the Fourth Amendment.” 662 F. 2d, at 518. We think that respondent’s contentions, and the above- quoted language from the opinion of the Court of Appeals, to some extent lose sight of the limited use which the govern- ment made of the signals from this particular beeper. As we have noted, nothing in this record indicates that the beeper ### Page 10 UNITED STATES v. KNOTTS 285 276 Bren na n , J., concurring in judgment signal was received or relied upon after it had indicated that the drum containing the chloroform had ended its automotive journey at rest on respondent’s premises in rural Wisconsin. Admittedly, because of the failure of the visual surveillance, the beeper enabled the law enforcement officials in this case to ascertain the ultimate resting place of the chloroform when they would not have been able to do so had they relied solely on their naked eyes. But scientific enhancement of this sort raises no constitutional issues which visual surveillance would not also raise. A police car following Petschen at a distance throughout his journey could have observed him leaving the public highway and arriving at the cabin owned by respondent, with the drum of chloroform still in the car. This fact, along with others, was used by the government in obtaining a search warrant which led to the discovery of the clandestine drug laboratory. But there is no indication that the beeper was used in any way to reveal information as to the movement of the drum within the cabin, or in any way that would not have been visible to the naked eye from out- side the cabin. Just as notions of physical trespass based on the law of real property were not dispositive in Katz v. United States, 389 U. S. 347 (1967), neither were they dis- positive in Hester n. United States, 265 U. S. 57 (1924). We thus return to the question posed at the beginning of our inquiry in discussing Katz, supra; did monitoring the beeper signals complained of by respondent invade any legiti- mate expectation of privacy on his part? For the reasons previously stated, we hold it did not. Since it did not, there was neither a “search” nor a “seizure” within the contempla- tion of the Fourth Amendment. The judgment of the Court of Appeals is therefore Reversed. Just ice Bren nan , with whom Justic e Mars hal l joins, concurring in the judgment. I join Justic e Blac kmu n ’s and Justic e Steve ns ’ opin- ions concurring in the judgment. I should add, however, ### Page 11 286 OCTOBER TERM, 1982 Bren na n , J., concurring in judgment 460 U. S. that I think this would have been a much more difficult case if respondent had challenged, not merely certain aspects of the monitoring of the beeper installed in the chloroform container purchased by respondent’s compatriot, but also its original installation. See ante, at 279, n. Katz n. United States, 389 U. S. 347 (1967), made quite clear that the Fourth Amend- ment protects against governmental invasions of a person’s reasonable “expectation^] of privacy,” even when those invasions are not accompanied by physical intrusions. Cases such as Silverman v. United States, 365 U. S. 505, 509-512 (1961), however, hold that, when the Government does en- gage in physical intrusion of a constitutionally protected area in order to obtain information, that intrusion may constitute a violation of the Fourth Amendment even if the same in- formation could have been obtained by other means. I do not believe that Katz, or its progeny, have eroded that princi- ple. Cf. The Supreme Court, 1979 Term, 94 Harv. L. Rev. 75, 203-204 (1980). I am also entirely unconvinced by the Court of Appeals’ footnote disposing of the installation issue with the state- ment: “we hold that the consent of the owner [of the chloro- form drum] at the time of installation meets the requirements of the Fourth Amendment, even if the consenting owner in- tends to soon sell the ‘bugged’ property to an unsuspecting buyer. Caveat emptor.” 662 F. 2d 515, 517, n. 2 (1981) (citation omitted). The Government is not here defending against a claim for damages in an action for breach of a war- ranty; it is attempting to justify the legality of a search con- ducted in the course of a criminal investigation. I am not at all sure that, for purposes of the Fourth Amendment, there is a constitutionally significant difference between planting a beeper in an object in the possession of a criminal suspect and purposefully arranging that he be sold an object that, unknown to him, already has a beeper installed inside it. Cf. Gouled v. United States, 255 U. S. 298, 305-306 (1921); Lewis v. United States, 385 U. S. 206, 211 (1966). ### Page 12 UNITED STATES v. KNOTTS 287 276 Bla ckmu n , J., concurring in judgment Respondent claimed at oral argument that, under this Court’s cases, he would not have standing to challenge the original installation of the beeper in the chloroform drum be- cause the drum was sold, not to him, but to one of his compa- triots. See ante, at 279, n. If respondent is correct, that would only confirm for me the formalism and confusion in this Court’s recent attempts to redefine Fourth Amendment standing. See Rawlings v. Kentucky, 448 U. S. 98, 114 (1980) (Mars hall , J., dissenting); Rakas v. Illinois, 439 U. S. 128, 156 (1978) (Whi te , J., dissenting). Justi ce Blackm un , with whom Justi ce Brennan , Jus - tic e Mars hall , and Justic e Steven s join, concurring in the judgment. The Court’s opinion gratuitously refers to the “open fields” doctrine and twice cites Hester v. United States, 265 U. S. 57 (1924). Ante, at 282 and 285. For me, the present case does not concern the open fields doctrine, and I regard these references and citations as unnecessary for the Court’s deci- sion. Furthermore, and most important, cases concerning the open fields doctrine have been accepted by the Court for argument and plenary consideration. State v. Brady, 406 So. 2d 1093 (Fla.), cert, granted, 456 U. S. 988 (1982); United States v. Oliver, 686 F. 2d 356 (CA6 1982), cert, granted, 459 U. S. 1168 (1983). See also United States v. Dunn, 674 F. 2d 1093 (CA5 1982), cert, pending, No. 82-508. It would be unfortunate to provide either side in these granted cases with support, directly or by implication, for its position, and I surely do not wish to decide those cases in this one. Although the Court does not indicate its view on how such cases should be decided, I would defer all comments about open fields to a case that concerns that subject and in which we have the benefit of briefs and oral argument. I therefore do not join the Court’s opinion. I concur only in the result it reaches. ### Page 13 288 OCTOBER TERM, 1982 Ste ve ns , J., concurring in judgment 460 U. S. Justi ce Stevens , with whom Justi ce Bren na n , and Justic e Mars hal l join, concurring in the judgment. Since the respondent in this case has never questioned the installation of the radio transmitter in the chloroform drum, see ante, at 279, n., I agree that it was entirely reasonable for the police officers to make use of the information received over the airwaves when they were trying to ascertain the ultimate destination of the chloroform. I do not join the Court’s opinion, however, because it contains two unnec- essarily broad dicta: one distorts the record in this case, and both may prove confusing to courts that must apply this deci- sion in the future. First, the Court implies that the chloroform drum was pa- rading in “open fields” outside of the cabin, in a manner tan- tamount to its public display on the highways. See ante, at 282. The record does not support that implication. As Jus - tice Blackm un points out, this case does not pose any “open fields” issue. Second, the Court suggests that the Fourth Amendment does not inhibit “the police from augmenting the sensory fac- ulties bestowed upon them at birth with such enhancement as science and technology afforded them.” Ibid. But the Court held to the contrary in Katz v. United States, 389 U. S. 347 (1967). Although the augmentation in this case was unobjectionable, it by no means follows that the use of electronic detection techniques does not implicate especially sensitive concerns. Accordingly, I concur in the judgment. **Wayback failure**: Save Page Now did not return a response during the bounded 2026-08-10 capture pass. Retry pending. ## Notes - Tier: 2 - primary public record or court opinion. - Cited by: [[ALPR Fourth Amendment Law Is Fact-Bound and Unsettled]].