Opinion
POCHÉ, J.This case presents the question of whether a warrantless scan made with a thermal imaging device of a private dwelling constitutes an unreasonable search within the meaning of the Fourth Amendment to the United States Constitution. We hold that it does.
Defendant, Dorian Deutsch, pleaded no contest to a single count of furnishing a room in a building for the cultivation of marijuana (Health & Saf. Code, § 11366.5). On appeal she contends that the trial court erred in denying her motion to suppress evidence which was seized in a search made with a warrant issued in part upon the basis of the thermal imager scan of her home. (Pen. Code, § 1538.5.) That evidence included some 200 cannabis plants which were being cultivated hydroponically under high wattage lights in 2 walled-off portions of the home’s garage.
According to the police officer’s affidavit offered in support of the search warrant a confidential informant gave a friend a ride to defendant’s home. When they arrived defendant gave the informant a small amount of dried marijuana as a thank you. The informant did not report seeing any growing cannabis plants inside the home, but did note that two doors in the living room were “blocked off with bedsheets.” The officer obtained a search warrant for utility records which showed “an unusually high electrical usage” which he concluded was “extremely consistent with the indoor cultivation of cannabis.” Some four days later, without having obtained a warrant the officer drove by the residence at 1:30 in the morning and scanned it with a thermal imager.
*1228As described in the officer’s affidavit a thermal imaging device is “a passive, nonintrusive system which detects differences in temperature at surface levels.” Such devices measure radiant energy in the thermal portion of the electromagnetic spectrum1 and display their readings showing areas which are relatively cold as nearly black, warmer areas in shades of gray and hot areas as white. (U.S. v. Porco (D.Wyo. 1994) 842 F.Supp. 1393, 1396.) With the imager the officer “observed high heat level readings, showing excessive heat release” from the “west side, north face, of the residence, which appeared to be the garage area.”
Discussion
1. Thermal Imaging
The warrantless use of thermal imaging devices has generated a considerable body of legal authority the bulk of which has sanctioned their use, concluding that their use is not an unreasonable search. A much smaller body of case law has rejected that view, and represents the better reasoned authority as applied to thermal imaging scans of private residences.
Defendant maintains that use of the thermal imager on her residence was a warrantless search conducted in violation of the right, under the Fourth Amendment to the United States Constitution “of the people to be secure in their persons, houses, papers and effects, against unreasonable searches . . . .” In Katz v. United States (1967) 389 U.S. 347 [19 L.Ed.2d 576, 88 S.Ct. 507] the Supreme Court rejected the notion that every impermissible governmental intrusion must involve a physical invasion or trespass. (Id. at p. 353 [19 L.Ed.2d at p. 583].) Instead, it read the protections of the amendment to foreclose a warrantless electronic interception of telephone calls made from a glass enclosed public phone booth. (Id. at pp. 348, 352 [19 L.Ed.2d at pp. 580, 582].) As articulated in Justice Harlan’s concurrence the appropriate test for Fourth Amendment purposes is twofold: first, the person must demonstrate an actual, subjective expectation of privacy in that which is searched and second, that expectation must be one our society recognizes to be reasonable. (Id. at p. 361 [19 L.Ed.2d at pp. 587-588] (cone. opn. of Harlan, J.).)
While Katz rejected strict categories of protected versus unprotected places, Justice Harlan noted the “home is, for most purposes, a place where *1229[one] expects privacy, but objects, activities, or statements that [one] exposes” there to outsiders may fall outside the protection of the amendment because the householder has displayed them freely and has shown no intention to keep them private. (Katz v. United States, supra, 389 U.S. at p. 361 [19 L.Ed.2d at p. 588] (cone. opn. of Harlan, J.).) More recently the Supreme Court has restated the particular deference accorded the home characterizing as a basic “Fourth Amendment principle” the notion that “private residences are places in which the individual normally expects privacy free of governmental intrusion not authorized by a warrant, and that expectation is plainly one that society is prepared to recognize as justifiable.” (United States v. Karo (1984) 468 U.S. 705, 714 [82 L.Ed.2d 530, 541, 104 S.Ct. 3296].)
Information or activities which are exposed to public view cannot be characterized as something in which a person has a subjective expectation of privacy, nor can they fulfill the second prong of Katz—as being that which society reasonably expects will remain private. A common theme of public disclosure which defeats privacy runs through many cases in which no search was found to have occurred: such as a mechanically recorded list of phone numbers dialed kept by the phone company which has been held to be as publicly disclosed as if the calls had been made through an operator (Smith v. Maryland (1979) 442 U.S. 735, 743-744 [61 L.Ed.2d 220, 228-229, 99 S.Ct. 2577]), or high resolution photographs of structures in an industrial building complex viewed from the air which are as available to government inspection as to that of any airborne passerby. (Dow Chemical Co. v. United States (1986) 476 U.S. 227, 237, fn. 4, 239 [90 L.Ed.2d 226, 237, 238, 106 S.Ct. 1819].) Accordingly, a warrantless thermal scan of an outbuilding located some 200-300 yards from a home has been upheld because the structure was in an “open field.” (U.S. v. Ishmael (5th Cir. 1995) 48 F.3d 850, 857.)
One who discards garbage by setting it out on the public street has renounced any expectation of privacy in the contents of his garbage bin. (California v. Greenwood (1988) 486 U.S. 35, 40 [100 L.Ed.2d 30, 36-37, 108 S.Ct. 1625].) Analogizing to the discarded garbage of Greenwood certain thermal imaging opinions have characterized the heat signatures registered by the device as “heat waste.” (U.S. v. Penny-Feeney (D.Hawaii 1991) 773 F.Supp. 220, 225, affd. on other grounds in U.S. v. Feeney (9th Cir. 1993) 984 F.2d 1053, 1056; U.S. v. Ford (11th Cir. 1994) 34 F.3d 992, 995; U.S. v. Myers (7th Cir. 1995) 46 F.3d 668, 669.) The analogy is neither good law nor good physics. As a recent decision from the Tenth Circuit points out, the thermal imager does not simply measure the waste heat radiating from a structure, but it measures all temperature differentials *1230across the exterior surface of the structure. (U.S. v. Cusumano (10th Cir. 1995) 67 F.3d 1497, rehg. granted Dec. 15, 1995.) Therefore, the function of the device is to paint an infrared picture of the heat sources which permits inferences about the heat generating activities occurring within the residence. (Id. at p. 1501.) Moreover, as the Cusumano court notes, the thermal imager is no more directed to measuring waste heat than the electronic bug affixed to the phone booth in Katz was directed to collecting waste sound waves. (Ibid.)
The principle that nondisclosed activities within the home are those in which society accepts a reasonable expectation of privacy and therefore activities which require a warrant for government intrusion is clearly set out in two Supreme Court beeper cases. In United States v. Karo, supra, 468 U.S. 705, drug enforcement agents arranged for a beeper to be inserted in a can of ether the agents believed was being obtained for the purpose of extracting cocaine from drug-impregnated clothing. (Id. at p. 708 [82 L.Ed.2d at p. 537].) Using the signals from the beeper the agents located the can in the course of its movements to a private residence, to two different storage facilities, and then to a second residence. (Id. at pp. 708-709 [82 L.Ed.2d at pp. 537-538].) The court concluded that the monitoring of the beeper when it was inside a private residence was an unreasonable search because “[t]he beeper tells the agent that a particular article is actually located at a particular time in the private residence and is in the possession of the person or persons whose residence is being watched.” (Id. at p. 715 [82 L.Ed.2d at p. 541].) While the court noted that the monitoring of the beeper was less intrusive than a full-scale search would be, nonetheless the beeper revealed information to the government which would not otherwise have been obtained without a search warrant. (Ibid.)
The outcome of Karo turned on the information conveyed to the monitoring agents by the beeper’s signals while it was within the residence and therefore the case was distinguished by the court from its holding a year earlier in United States v. Knotts (1983) 460 U.S. 276 [75 L.Ed.2d 55, 103 S.Ct. 1081]. In Knotts a beeper was inserted into a drum of chloroform which authorities believed would be used for the manufacture of illicit drugs. However, in that case the beeper was monitored only on its journey over public roadways up to the time the drum was transferred into a private residence. (Id. at p. 278 [75 L.Ed.2d at pp. 59-60].) Reasoning that there was “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 outside the cabin,” the court upheld the monitoring of the beeper. (Id. at p. 285 [75 L.Ed.2d at p. 64].) Like the beeper signal being monitored inside the residence in Karo the thermal *1231imaging scan of defendant’s residence told the police something about activities within the house which they could not otherwise have learned without obtaining a warrant to search it.
To suggest that a thermal scan passes constitutional muster because it is not intrusive becomes a circular argument. The People argue that the thermal scan does not reveal personal, intimate details about what occurs inside the home. Sometimes the argument is made that the imprecision of the scan reveals only heat signatures which lack sufficient clarity to paint images of exactly what inside the house is the source of the heat. In short, the scan cannot distinguish between a marijuana grow room and a hydroponic tomato farm. In fact in one reported case the only “hot spot” found by the thermal scan used to support a search warrant of the premises, turned out to be a “standard household dehumidifier” located in the residence, while in fact marijuana was being grown in an outbuilding. (U.S. v. Field (W.D.Wis. 1994) 855 F.Supp. 1518, 1523-1525.) Precisely because the thermal imager is indiscriminate in registering sources of heat it is an intrusive tool, which tells much about the activities inside the home which may be quite unrelated to any illicit activity. In this respect it is the very antithesis of a dog sniff because the trained narcotics dog alerts only in the presence of contraband (United States v. Place (1983) 462 U.S. 696, 707 [77 L.Ed.2d 110, 120-121, 103 S.Ct. 2637])2 whereas the thermal imager indiscriminately registers all sources of heat.
Defendant demonstrated a subjective expectation of privacy in the activities she conducted inside her home. The grow rooms found in her garage were walled off, and the view by visitors into the rest of her house from the living room was blocked by bedsheets hung over the doorways. We find that society recognizes as reasonable an expectation that the heat generated from within a private residence may not be measured by the government without a warrant permitting such a search. In this instance the warrantless thermal scan of defendant’s home was an unreasonable search prohibited by the Fourth Amendment.
*12322. Sufficiency of the Affidavit
Defendant maintains that without the results of the impermissible thermal scan made of her residence the affidavit providing a basis for issuance of the search warrant falls short of establishing probable cause. Probable cause is a “strong suspicion” that what is being sought will be in the location to be searched. (Wimberly v. Superior Court (1976) 16 Cal.3d 557, 564 [128 Cal.Rptr. 641, 547 P.2d 417].) The magistrate who issues the warrant must conclude whether, given the totality of the circumstances set out in the affidavit, there is a fair probability that the evidence sought will be located at the scene of the search. (Illinois v. Gates (1983) 462 U.S. 213, 238-239 [76 L.Ed.2d 527, 548-549, 103 S.Ct. 2317].) On appeal we accord the magistrate’s determination great deference, inquiring only whether there was a substantial basis to conclude that the warrant would uncover evidence of crime. (Id. at p. 236 [76 L.Ed.2d at pp. 546-547].)
The affidavit submitted by Detective Watkins recounted that the confidential informant was not only given a small amount of marijuana while inside the home, but also detected “a heavy odor of marijuana” there. The informant also noted that doorways in the living room area were blocked by bedsheets. In addition to the information from the informant, Detective Watkins obtained with a warrant records of the electrical consumption at the residence. Those records showed that electrical consumption was “up to seven times the baseline quantity rate” which in the opinion of the officer was “extremely consistent with the indoor cultivation of cannabis.”
In his affidavit the officer recounted a considerable personal experience with narcotics investigations and arrests, including seven prior warrants for indoor growing of cannabis. The opinions of an experienced officer may legitimately be considered by the magistrate in making the probable cause determination. (People v. Tuadles (1992) 7 Cal.App.4th 1777, 1784 [9 Cal.Rptr.2d 780].) Given the totality of the information set out in the affidavit after excising the results of the thermal scan, we can say that there was a substantial basis to support a strong suspicion that there was evidence of a crime to be found in defendant’s home.3 The trial court did not err in denying the motion to suppress/motion to traverse the search warrant.
*12333. Denial of Franks Hearing*
Disposition
Although we hold that the warrantless use of the thermal imager upon defendant’s residence violates the Fourth Amendment, we nonetheless affirm because even without the results of the thermal scan the affidavit provides a substantial basis for the magistrate’s finding of probable cause to search. (Illinois v. Gates, supra, 462 U.S. at p. 238 [76 L.Ed.2d at p. 548].)
The judgment of conviction is affirmed.
Reardon, J., concurred.
The thermal imager differs from infrared devices (such as night vision goggles) in that the latter amplify the infrared spectrum of light whereas the thermal imager registers solely that portion of the infrared spectrum which we call heat. (Comment, A High-Tech Assault on the ‘Castle’: Warrantless Thermal Surveillance of Private Residences and the Fourth Amendment (1995) 90 Nw. U. L.Rev. 267, 280, fn. 100.)
Dog sniff cases, those in which dogs specially trained to alert to the odor of certain types of contraband, have been characterized by our Supreme Court as sui generis. (United States v. Place, supra, 462 U.S. 696, 707 [77 L.Ed.2d 110, 120-121].) In Place a sniff of luggage conducted at an airport was upheld as not a search within the meaning of the Fourth Amendment. (Ibid.) Similarly a dog sniff of a warehouse conducted from an alley open to the public was upheld in U.S. v. Lingenfelter (9th Cir. 1993) 997 F.2d 632, and a sniff of a semitrailer parked by a gas station in an area open to the public was likewise allowed in United States v. Solis (9th Cir. 1976) 536 F.2d 880. In U.S. v. Colyer (D.C. Cir. 1989) 878 F.2d 469 [278 App.D.C. 367] a dog sniff of a railway sleeping compartment made from the train corridor was upheld after the court concluded that although a sleeping car “may in some ways resemble a residence, it enjoys no such status in the law." (Id. at p. 476.)
In light of our conclusion in part 1 that the warrantless use of the scan was impermissible we need not reach defendant’s additional contention that the results of that scan as conveyed in conclusory terms in the affidavit formed an inadequate factual basis for the magistrate’s determination.
See footnote, ante, page 1224.