This criminal prosecution requires us to determine the appropriate standard for the warrantless installation of an electronic tracking device (a “beeper”) on the exterior of a vehicle parked in a public place. The question remains one of first impression for this circuit because of our equally divided vote when considering the same issue in United States v. Holmes, 537 F.2d 227 (5th Cir. 1976) (en banc); see id. at 228 (Ainsworth, J., dissenting). As in Holmes, this case was placed en banc because of its exceptional importance.1
Defendant-appellee Barry Dean Michael was indicted on two counts: unlawfully manufacturing and possessing with the intent to distribute a Section II Controlled Substance, methylenedioxyamphetamine (MDA), and conspiring to distribute MDA in violation of 21 U.S.C. §§ 841(a)(1) and 846. Michael moved to suppress certain evidence as unconstitutionally seized. The district court, relying on the panel opinion in Holmes,2 granted Michael’s motion to suppress with respect to evidence seized from a warehouse pursuant to a warrant, but which DEA agents had discovered through the warrantless installation of a beeper on the exterior of a van which Michael had rented. R. at 118-120. A panel of this court, relying both on its independent analysis and on the Holmes panel opinion,3 affirmed the district court. United States v. Michael, 622 F.2d 744 (5th Cir. 1980). The court voted to rehear this case en banc, United States v. Michael, 628 F.2d 931 (5th *255Cir. 1980), thus vacating the panel opinion. See Fifth Circuit Local Rule 17. We reverse the judgment of the district court.
I. THE FACTS
In early 1978, an employee of Scientific Products, a chemical supply house in Atlanta, Georgia, notified Drug Enforcement Administration (DEA) agents that Andrew Welch was purchasing large quantities of glassware and equipment of the type used in clandestine drug laboratory operations. Upon further investigation, a team of agents led by Agent James Sweat learned that Welch was also purchasing chemicals from Burris Chemical Company in Atlanta. In particular, they discovered that Welch had purchased a barrel of acetone and a barrel of formic acid in December 1977. Both acetone and formic acid can be used to manufacture MDA.
On August 8,1978, an employee of Burris Chemical Company notified the DEA that a “Mike Thompson” had purchased a large quantity of acetone, 20 gallons, that day and had made several previous purchases. About the same time, Agent Sweat learned that “Mike Thompson” had returned the empty acetone drum from Welch’s December 1977 purchase and had directed the dejposit be sent to Welch. Also early in August, Burris employees told Agent Sweat that on July 20 Welch had purchased some muriatic acid, another chemical used in the manufacture of MDA.4 At this time, Agent Sweat told the Burris employee to let Sweat know if “Mike Thompson” ever ordered any more chemicals.
At lunch time on August 10, the Burris employee contacted Agent Sweat to tell him “Mike Thompson” had ordered another drum of acetone and that “Thompson” usually picked up his order within the hour. Agent Sweat and his partner arrived at Burris before “Thompson” and saw “Thompson” load the acetone into a van.5 The agents followed the van by visual surveillance until “Thompson” parked in a lot adjoining a pizza restaurant and went inside. While “Thompson” was inside the restaurant, Agent Sweat’s partner, Agent Smith, installed a beeper on the exterior of the van without first obtaining a warrant.
Further investigation by the DEA established that “Mike Thompson” was an alias used by appellee Barry Dean Michael. Subsequent monitoring of the beeper placed on Michael’s van ultimately led the DEA agents to a warehouse where, pursuant tó a warrant, they seized the chemicals, equipment, and quantities of MDA which are the subject of Michael’s suppression motion.
II. THE LAW
We look to the fourth amendment to determine whether the facts in this case, as related above, provide a sufficient basis for the warrantless installation of a beeper on Michael’s van. The fourth amendment, in pertinent part, protects people’s “persons, houses, papers, and effects, against unreasonable searches and seizures.” Although originally viewed as protecting property rights of individuals, the Supreme Court has now rejected the idea that fourth amendment coverage turns on “arcane distinctions developed in property ... law.” Rakas v. Illinois, 439 U.S. 128, 143, 99 S.Ct. 421, 430, 58 L.Ed.2d 387 (1978). Instead, the fourth amendment protects individuals *256from violations of their legitimate or reasonable expectations of privacy. See id.; Katz v. United States, 389 U.S. 347, 361, 88 5. Ct. 507, 516, 19 L.Ed.2d 576 (1967) (Harlan, J., concurring); Jones v. United States, 357 U.S. 493, 498, 78 S.Ct. 1253, 1256, 2 L.Ed.2d 1514 (1958). Expectation of privacy analysis is especially appropriate in cases like the instant one which involve an individual’s rights with respect to an automobile.6 In Cardwell v. Lewis, 417 U.S. 583, 591, 94 S.Ct. 2464, 2470, 41 L.Ed.2d 325 (1974) (plurality opinion), Justice Blackmun stated, “[I]nsofar as Fourth Amendment protection extends to a motor vehicle, it is the right to privacy that is the touchstone of our inquiry.”
In addition, fourth amendment cases have recognized that the degree of intrusion into a suspect’s privacy is relevant in deciding whether any of the suspect’s constitutional rights have been infringed. Thus, “intrusions into the human body,” because of their extremely invasive nature, require more justification to satisfy the fourth amendment,7 than does a limited stop and frisk.8 Likewise, the ransacking of a suspect’s house in search of evidence requires more justification for the intrusion9 than does the examination of a suspect’s automobile to discover its vehicle identification number.10 Applying this dual privacy and intrusiveness analysis to the facts of the instant case, we hold that the minimal intrusion involved in the attachment of a beeper to Michael’s van, parked in a public place, was sufficiently justified so as to satisfy any of Michael’s fourth amendment expectation of privacy concerns.
III. APPLICATION
We note that some members of the majority would hold that the installation of the beeper on the van is not a search or seizure at all, and thus does not implicate any fourth amendment interests. While we do not reject this view, we feel that under the facts presented, the installation of the beeper was permissible even if we assume the installation was a search.11
*257The facts known to the DEA agents at the time they placed the beeper were enough to give them a reasonable suspicion that Michael was engaged in criminal activity. That is to say, specific and articulable facts, together with rational inferences from those facts, reasonably warranted the agents in the belief12 that Michael was involved in the illicit manufacture of MDA. The agents had been told that Michael and Welch were associated. The agents had probable cause to believe Welch was manufacturing MDA, United States v. Michael, 622 F.2d 744, 745 n.4 (5th Cir. 1980), and the agents knew Michael had purchased chemicals consistent with the manufacture of MDA on several occasions. We are supported in our view that the facts establish reasonable suspicion in light of the panel’s similar conclusion. Id. However, the district court found, “The evidence that was seized from the warehouse was the product of an unlawful search and therefore subject to exclusion,” (R. at 118) since the DEA agents obtained no warrant to install the beeper which led them to the evidence. Likewise, the panel would have allowed warrantless use of the beeper only if both probable cause and exigent circumstances existed. United States v. Michael, supra at 752. We disagree with the district court and the panel and hold that reasonable suspicion is adequate to support warrantless beeper installation.13
A. Privacy
First, as we have said, Michael’s fourth amendment rights in this case turn upon his reasonable expectations of privacy. However, search and seizure cases involving vehicles have recognized that an individual’s expectation of privacy in his automobile is less than in other property. The Supreme Court has stated:
But this Court has recognized significant differences between motor vehicles and other property which permit warrantless searches of automobiles in circumstances in which warrantless searches would not be reasonable in other contexts.
The answer lies in the diminished expectation of privacy which surrounds the automobile. ...
United States v. Chadwick, 433 U.S. 1, 12, 97 S.Ct. 2476, 2484, 53 L.Ed.2d 538 (1977); see also United States v. Foskey, 636 F.2d 517 (D.C. Cir. 1980). In this case, Michael’s van was parked in plain view, in a public place. Michael drove the van on public roads during the daytime. The Supreme Court said in Cardwell:
A car has little capacity for escaping public scrutiny. It travels public thoroughfares where its occupants and its contents are in plain view, [citation omitted] “What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment pro*258tection.” Katz v. United States, 389 U.S., at 351, 88 S.Ct., at 511; United States v. Dionisio, 410 U.S. [1] at 14, 93 S.Ct. [764] at 771 [35 L.Ed.2d 67],
417 U.S. at 590-91, 94 S.Ct. at 2469-70. As the cases demonstrate, Michael’s legitímate expectation of privacy with respect to the movements of his automobile was substantially reduced.14
B. Intrusiveness
Second, the intrusion occasioned by the placement of the beeper was not great. Although the attachment was technically a trespass, “arcane distinctions developed in property . .. law” are not controlling. The Supreme Court has permitted the removal of paint scrapings from the exterior of an automobile, observing “[W]e fail to comprehend what expectation of privacy was infringed. Stated simply, the invasion of privacy, ‘if it can be said to exist, is abstract and theoretical.’ Air Pollution Variance Board v. Western Alfalfa Corp., 416 U.S. 861, 865, 94 S.Ct. 2114, 2116, 40 L.Ed.2d 607 (1974).” Cardwell v. Lewis, 417 U.S. at 591-92, 94 S.Ct. at 2470 (1974). Similarly, this court, sitting en banc, has allowed police officers without warrants to open vehicle doors to determine the correct identification numbers on the side panel. United States v. Johnson, 431 F.2d 441 (5th Cir. 1970) (en banc).
We find that the DEA agents’ reasonable suspicion that Michael was engaged in criminal activity justified the placement and monitoring of the beeper. The actual installation of the beeper was much less intrusive than the typical stop and frisk. Michael was in the pizza restaurant when the installation took place. He was not detained or questioned; he suffered no indignity; 15 nothing from the interior of the van was» seized or searched; indeed, nothing even from the van’s exterior was removed. See Cardwell v. Lewis, 417 U.S. at 591, 94 S.Ct. at 2470. The subsequent monitoring also did not violate Michael’s reasonable expectation of privacy. The beeper only aided the agents in the performance of their lawful surveillance.16 The van traveled public roads and was exposed to public view. Monitoring the beeper while the agents had reasonable suspicion to believe Michael was conspiring to manufacture MDA did not violate his fourth amendment rights.
*259C. Competing Interests
Third, we consider the governmental interest in eliminating illegal drug manufacture to be a persuasive reason to permit this minimally intrusive practice.17 An “intermediate response” based on something less than probable cause,18 is a proper investigatory tool to aid DEA agents in discovering and eliminating clandestine laboratory operations. In balancing the public concerns served by the use of the beeper, to discover Michael’s drug manufacturing apparatus against the slight infringement of Michael’s expectation of privacy, we find the beeper’s use to be eminently reasonable. We hold that the installation and monitoring of the beeper involved no violation of Michael’s fourth amendment rights. Accordingly, we reverse the district court’s suppression of the evidence seized at the warehouse.
REVERSED.
. Fed.R.App.P. 35(a); Fifth Circuit Local Rule 16.2.4.
. It was error for the district judge to follow the panel opinion in United States v. Holmes, 521 F.2d 859 (5th Cir. 1975), as precedent. The court’s vote to put Holmes en banc vacated the panel opinion. See Local Rule 17. A vacated judgment leaves the case as if no decision had been entered. See, e. g., Lantz v. Vai, 199 Cal. 190, 193, 248 P. 665, 665 (1926); Clarke v. Baird, 98 Cal. 642, 644, 33 P. 756, 756-57 (1893); In re Edwards, 25 Cal.App.3d 906, 912, 102 Cal.Rptr. 216, 220 (2d Dist. 1972); Adel-helm v. Dougherty, 129 Fla. 680, 683, 176 So. 775, 777 (1937); Talley v. Alton Box Board Co., 37 Ill.App.2d 137, 138, 185 N.E.2d 349, 350 (4th Dist. 1962); Luck v. Hopkins, 92 Tex. 426, 428, 49 S.W. 360, 361 (1899); Sawyer v. Donley County Hosp. Dist., 513 S.W.2d 106, 109 (Tex. Civ.App. — Amarillo 1974, no writ); 49 C.J.S. Judgments § 306 (1947). United States v. Conroy, 589 F.2d 1258, 1263 (5th Cir. 1979), is not to the contrary.
. The panel in Michael independently adopted the reasoning of the Holmes panel and did not view Holmes as precedent. See United States v. Michael, 622 F.2d 744, 744 n.1 (5th Cir. 1980).
. In late July, the DEA agents also learned that Janice Christie had been arrested by the Georgia Bureau of Investigation for possession of one pound of MDA (R. vol. II at 23-24). The vehicle Christie was driving was registered to Andrew Welch. Inside the vehicle, GBI agents found a receipt for 500 pounds of iso-safrole, another chemical used to make MDA, made out to “Mike Johnson.” Later investigation revealed that “Johnson” was an alias of appellee Michael.
Although Agent Sweat stated that on August 10 he had not connected Michael with the purchase of iso-safrole (R. vol. II at 76), the GBI arrest of Christie, of which the DEA agents were aware, supports the agents’ belief that Welch and his associates were engaged in the manufacture of MDA.
. After observing a man believed to be “Mike Thompson” pick up some chemicals at Burris, Agent Sweat’s partner, Agent Smith, radioed the DEA office and had the operator call Burris Chemical Company to make sure the individual was “Mike Thompson.” R. vol. II at 127-28.
. The circuits that have considered the permissibility of installing beepers have used a privacy analysis. See, e. g., United States v. Bailey, 628 F.2d 938, 940 (6th Cir. 1980) (petition for rehearing pending); United States v. Bernard, 625 F.2d 854, 860 (9th Cir. 1980); United States v. Bruneau, 594 F.2d 1190, 1196 (8th Cir.), cert. denied, 444 U.S. 847, 100 S.Ct. 94, 62 L.Ed.2d 61 (1979); United States v. Washington, 586 F.2d 1147, 1157 (7th Cir. 1978); United States v. Clayborne, 584 F.2d 346, 348 (10th Cir. 1978); United States v. Moore, 562 F.2d 106, 110 (1st Cir. 1977).
. Schmerber v. California, 384 U.S. 757, 770, 86 S.Ct. 1826, 1835, 16 L.Ed.2d 908 (1966) (warrant supported by probable cause).
. Terry v. Ohio, 392 U.S. 1, 20, 88 S.Ct. 1868, 1879, 20 L.Ed.2d 889 (1968); id. at 33, 88 S.Ct. at 1886 (Harlan, J., concurring) (reasonable “articulable suspicion”). See Adams v. Williams, 407 U.S. 143, 92 S.Ct. 1921, 32 L.Ed.2d 612 (1972). This circuit has recognized that whether something less than probable cause may justify a search depends in part on the intrusiveness of that search. In United States v. Afanador, 567 F.2d 1325, 1328 (5th Cir. 1978), we said, “Thus, what constitutes ‘reasonable suspicion’ to justify a particular search may not suffice to justify a more intrusive or demeaning search.” See also United States v. Smith, 557 F.2d 1206, 1209 n.6 (5th Cir. 1977), cert. denied, 434 U.S. 1073, 98 S.Ct. 1259, 55 L.Ed.2d 777 (1978); United States v. Himmelwright, 551 F.2d 991, 994 (5th Cir.), cert. denied, 434 U.S. 902, 98 S.Ct. 298, 54 L.Ed.2d 189 (1977).
. Payton v. New York, 445 U.S. 573, 589-90, 100 S.Ct. 1371, 1381-82, 63 L.Ed.2d 639 (1980) (warrant supported by probable cause). See Lewis v. United States, 385 U.S. 206, 210, 87 S.Ct. 424, 427, 17 L.Ed.2d 312 (1966).
. United States v. Johnson, 431 F.2d 441 (5th Cir. 1970) (en banc) (no warrant or probable cause necessary). See South Dakota v. Opper-man, 428 U.S. 364, 367, 96 S.Ct. 3092, 3096, 49 L.Ed.2d 1000 (1976); United States v. Martinez-Fuerte, 428 U.S. 543, 561, 96 S.Ct. 3074, 3084-85, 49 L.Ed.2d 1116 (1976).
. It is difficult to classify the actions taken by the DEA agents in this case as either a search or seizure. See United States v. Bailey, 628 F.2d 938, 940 (6th Cir. 1980). The panel opinion relied on “pre-Katz jurisprudence” to find that the attachment of the beeper without the consent of someone with a possessory interest in the van was a search. United States v. Michael, 622 F.2d 744, 749 (5th Cir. 1980). However, as we have pointed out, analysis of search and seizure cases in terms of property law has now been replaced by reasonable ex*257pectation of privacy analysis. See note 5, supra, and accompanying text.
. See Brown v. Texas, 443 U.S. 47, 51, 99 S.Ct. 2637, 2641, 61 L.Ed.2d 357 (1979); Terry v. Ohio, 392 U.S. 1, 21, 88 S.Ct. 1868, 1880, 20 L.Ed.2d 889 (1968); United States v. Cimino, 631 F.2d 57, 59 (5th Cir. 1980).
. The other circuits have reached widely varying results for determining the proper standard . for the warrantless use of a beeper. The Ninth Circuit analyzes the installation and the monitoring of the beeper separately. Some Ninth Circuit cases have held that neither installation nor monitoring infringes a privacy interest, United States v. Pretzinger, 542 F.2d 517, 520 (9th Cir. 1976); United States v. Hufford, 539 F.2d 32, 34 (9th Cir.), cert. denied, 429 U.S. 1002, 97 S.Ct. 533, 50 L.Ed.2d 614 (1976). Another has held that installation might “violate fourth amendment precepts,” United States v. Miroyan, 577 F.2d 489, 492 (9th Cir.), cert. denied, 439 U.S. 896, 99 S.Ct. 258, 58 L.Ed.2d 243 (1978).
The Sixth Circuit appears to require nothing less than a warrant, at least for the attachment and monitoring of beepers on goods. United States v. Bailey, 628 F.2d 938 (6th Cir. 1980). But see id. at 942, 947 (may be no expectation of privacy as to public travels of a vehicle). The First Circuit ostensibly requires probable cause, although the court left open the possibility of a “reasonable cause” standard. United States v. Moore, 562 F.2d 106, 113 n.3 (1st Cir. 1977), citing United States v. Holmes, 537 F.2d 227, 228 (5th Cir. 1976) (en banc) (Ainsworth, J., dissenting). The holdings of the other circuits are discussed in United States v. Michael, 622 F.2d 744, 747-48 (5th Cir. 1980).
. The Government argues with considerable cogency that this case is governed by Smith v. Maryland, 442 U.S. 735, 99 S.Ct. 2577, 61 L.Ed.2d 220 (1979). In that case the Supreme Court held that installation and use of a pen register at the telephone company’s central office to record the numbers dialed by the defendant was not a search and violated no expectation of privacy. Id. at 743, 99 S.Ct. at 2581. The Court reasoned that since telephone users convey numerical information to the phone company which can be permanently recorded, they have no reasonable expectation that the phone company would not disclose those numbers to the police. Id. at 744, 99 S.Ct. at 2581-82.
The reasoning in the instant case is even more straightforward; no two-step disclosure is required. In driving on public roads, Michael was disclosing his van’s whereabouts directly to all law enforcement officials who cared to observe. The beeper, like the pen register in Smith, facilitated such observation. That the beeper required the DEA agents to make a technical trespass unlike the pen register in Smith is not controlling. This slight physical intrusion is insignificant if it infringes no privacy interest. Thus, although we do not necessarily adopt the reasoning in Smith so completely as to find that the attachment and use of the beeper was free from fourth amendment concerns, we recognize that under Smith, Michael’s expectation of privacy in this case was slight.
. See Terry v. Ohio, supra, 392 U.S. at 17-18, 88 S.Ct. at 1877.
. At oral argument, Michael’s counsel called our attention to the recent Second Circuit case of United States v. Taborda, 635 F.2d 131 (2d Cir. 1980). Taborda held that binocular-enhanced viewing of the interior of a home may violate a defendant’s reasonable expectation of privacy. Although there exists some authority for the opposite view, United States v. Hufford, 539 F.2d 32, 34 (9th Cir.), cert. denied, 429 U.S. 1002, 97 S.Ct. 533, 50 L.Ed.2d 614 (1976); United States v. Grimes, 426 F.2d 706, 708 (5th Cir. 1970), our holding today does not contradict Taborda. The police in Taborda were viewing into a private home, not observing the open movements of a motor vehicle on the public highways. See United States v. Allen, 633 F.2d 1282 (9th Cir. 1980).
. The governmental interest in deterring criminal conduct may properly be balanced against an individual’s privacy interests in fourth amendment cases. See, e. g., Bell v. Wolfish, 441 U.S. 520, 559, 99 S.Ct. 1861, 1885, 60 L.Ed.2d 447 (1979); United States v. BrignoniPonce, 422 U.S. 873, 878, 95 S.Ct. 2574, 2579, 45 L.Ed.2d 607 (1975). In United States v. Himmelwright, this court stated:
“[R]easonableness” in the fourth amendment sense always depends upon a balance which must be struck between, on the one hand, the level of official intrusion into an individual privacy and, on the other hand, the public interest to be served by such an intrusion.
551 F.2d 991, 994 (5th Cir. 1977).
. Adams v. Williams, supra, 407 U.S. at 145, 92 S.Ct. at 1921, 1923 (1972).