Smayda and Gunther were convicted of violating the “Assimilative Crimes” Act, 18 U.S.C. § 13.1 The offense was committed within Yosemite National Park, concededly a place of the type referred *252to in the section and in 18 U.S.C. § 7. The crime, oral copulation, is made punishable by the California Penal Code, Section 288a. Both defendants appeal. Their attack upon the judgment is based entirely upon their claim that all of the evidence against them was obtained in violation of their rights as defined in the Fourth Amendment to the Constitution:
“The right of the people to be secure in their persons, houses, papers and effects against unreasonable searches and seizures, shall not be violated * *
The offense occurred in a men’s toilet and washroom, at Camp Curry, a resort in the Park maintained and operated by the Yosemite Park & Curry Co., a government concessionaire. The particular facility is in a portion of the resort where tent-cabins, equipped for the accommodation of guests, are located. It is maintained primarily for the use of guests, but appears to be open, like most such facilities in hotels, to the public. In the men’s section of the building, which is enclosed by walls having windows in them set with the sills about 5 or 6 feet from the floor, there are wash basins, a urinal and three toilets. The latter are separately enclosed in stalls set side by side. The back wall of all three is a floor to ceiling partition, behind which is a space for getting at the pipes and similar purposes. One stall, which we call No. 1, is set at the side of the room, so that one of its sides is also a solid wall, from floor to ceiling. The partitions between the stalls and the exterior side wall of the third stall in the row (No. 3) are each made of a single thickness of boards, beginning about 18 inches above the floor and extending to about 3 feet from the ceiling, or a height of about 6 feet. Each stall has a door that swings inward and rests against a jamb when closed. The bottom of the door is a few inches higher above the floor than the bottom of the partitions and the top a few inches lower than the top of the partitions. The doors do not automatically swing shut and there is no lock, latch, or bolt with which to fasten them from the inside. Thus, an occupant of the stall cannot prevent someone else from entering except by holding the door shut. There is a light bulb in the ceiling just outside the door of the center stall (No. 2), and other light bulbs are in the main room, but none is over the stalls themselves. Above the whole restroom, under a peaked roof, is an open space or attic.
In the summer of 1963, between Memorial Day and July 13, both the manager of the resort and the park rangers, who also serve as park police, received complaints and information and themselves observed persons and conduct, indicating to them that restroom 600 was being used by homosexuals as a “hangout” and a place in which homosexual activities were being carried on. Persons unknown had cut holes in the two partitions separating stall No. 2 from stalls Nos. 1 and 3, each hole being about 2 inches square and about waist high from the floor. There were stains indicating use of these holes for lewd purposes. There were also smaller holes through which one using a toilet could peer into the adjoining stall. We do not detail all of the evidence in this regard; it was ample to give the manager and the rangers reasonable cause to believe that the stalls in restroom 600 had been and would be used in violation of Penal Code section 288a.
As a result, the manager of the resort discussed the problem with Ranger Twight, the law enforcement specialist in the Park, and it was decided that a hole should be cut in the ceiling over each stall, for purposes of observation. This was done, each hole being about 6 inches square and covered with a screen so as to make it look like an air vent. It was believed that criminal acts were most likely to occur at night, and particularly Saturday night, so that Ranger Twight decided to conduct surveillance on Saturday evening “after the family-type people had quit using the facility.” Surveillance was conducted first on the night of July 13 from 11:00 P.M. to mid*253night. Twight and a photographer were in the attic, and two rangers with a radio were outside where they could be called immediately. Some 25 or 30 persons were observed who simply made the normal use of the stall. Others were seen who peered through holes in the partitions, looked at each other over the partitions, masturbated, and at least two of whom performed an indecent act through the hole in the partition, but not in violation of P.C. § 288a. No arrests were made.
On July 20, similar surveillance was begun at 11:00 P.M. Six or seven persons whose behavior was normal were observed. Within five minutes after the surveillance began appellant Gunther appeared and entered one of the stalls. He remained for about 15 minutes, masturbated, and peered through the holes. He then left. A hand reached up and unscrewed the light bulb in front of the stalls. The officers could not see whose hand it was. Gunther returned shortly, and went through the same performance for about 15 minutes. He again left, returned and entered stall No. 2. Smayda then came in and entered stall No. 1. They peered at each other, masturbated, and then committed the crime through the hole in the partition. Photographs were taken. Twight, by radio, summoned the waiting rangers, and the appellants were arrested.
The record makes it clear that, while there was reason to believe that someone might commit the offense that evening, there was no reason to believe, at any time until after each appellant entered a stall, that that particular person was about to commit it.
Appellants rely primarily upon two California cases, Bielieki v. Superior Court, 1962, 57 Cal.2d 602, 21 Cal.Rptr. 552, 371 P.2d 288 and Britt v. Superior Court, 1962, 58 Cal.2d 469, 24 Cal.Rptr. 849, 374 P.2d 817. In each case, under quite similar circumstances,2 it was held that the surveillance was an unreasonable search, forbidden by both Article I § 19 of the California Constitution and the Fourth Amendment to the United States Constitution, and that evidence thus obtained was inadmissible.
It is suggested that we should follow these cases because, under the Assimilative Crimes Act, we are applying California law, and it would be anomalous if the defendants could be convicted under that Act of an offense for which they could not be convicted in a California court. We do not agree. The Assimilative Crimes Act creates a federal offense; it refers to the California statutes for its definition and its penalty,3 but it does not incorporate the whole criminal and constitutional law of California.4 In a federal court, the question of whether evidence was unlawfully obtained, and should therefore be excluded, is a federal question. We look, then, to the Constitution of the United States, not that of California. A decision of the Supreme Court of California, construing the Constitution of the United States, while entitled to great respect, is not binding upon the federal courts.
Our question then is, does the Fourth Amendment forbid what was done here ? We hold that it does not, on two alternative grounds: (1) If the ranger’s conduct was a “search,” appellants impliedly consented to it by doing what they did where they did it, and (2) there was no *254“unreasonable search” within the meaning of the amendment.
1. The District Judge, after hearing the testimony and examining photographs of the stalls, received in evidence as exhibits, reached the following conclusion :
“ * * . * I looked at the pictures and I think that there is something that we have got to consider here in the physical set-up of this bathroom and the physical characteristics of these doors. Mr. Porterfield in his argument referred to the train lobby observation point where the con man was witnessed making evidently some fast change and the Court held that he was out in the public when he was under surveillance, and, nevertheless, this was not an invasion of his privacy, and I attempted to distinguish that situation from that of where the person is in the extreme privacy of a lavatory, and that on the one hand he expects the whole world to see what he is doing, whereas, in the privacy of a toilet, he could not expect the whole world to see what he was doing. But viewing these pictures, a great deal of the privacy is taken out of these toilet stalls by the fact that they’re wide open for three feet at the top and they’re wide open for approximately 18 inches at the bottom. They are almost public. When a person goes into a stall of this type, the only reason for that door, in my opinion, is to shield the person who uses the lavatory from the very intimate details. When Mr. Twight could testify from out in the lobby that he could tell whether the man had his pants up or down in the customary fashion, a great deal of the privacy certainly is gone from the transaction that the person went in there to consummate.” V'«
We agree. Confining our ruling to the facts of this case, we think that, when people resort to such a public toilet for criminal purposes, they deliberately take the chance that they may be observed by police officers, and that they are not protected from such observation, whether clandestine or otherwise, because they choose to use the most nearly “private” part of such a facility — the toilet stall, which is customarily partially partitioned off, but for the provision of at least a minimum of public decency. The language of the California District Court of Appeal in People v. Young, 1963, 214 Cal.App.2d 131, 29 Cal.Rptr. 492, is, we think, persuasive here:
“Judges can take judicial knowledge from the case files in their own courts that public toilets in metropolitan parks, terminals, theatres, department stores and in similar places, frequented daily by masses of people, are often the locale of vice of many kinds such as sexual perversion, sale of narcotics, petty thefts, robbery and assaults. To hold that the public areas of such toilets are to be ‘off limits’ from clandestine surveillance by police would be to encourage the use of such places by perverts, panderers, pickpockets, addicts and hoodlums. Such persons would seek asylum or refuge in such places with the assurance that they could conduct their illicit activities therein while fully protected from the secret surveillance of the vice squad. Should the areas of such toilets, where the members of the public are free to circulate, as distinguished from areas where one may seclude oneself from public view, such as in an enclosed commode or toilet stall, become areas removed from such secret surveillance by the police, the peril to immature and innocent youth would be increased immeasurably. By leaving a ‘spotter’ or ‘lookout’ at the door to warn other perverts or degenerates of the approach of police, such immoral persons could conduct their illicit activities in full view of impressionable youths. Parents would not rest secure that their youngsters could use such facilities without fear that they would wit*255ness scenes of shocking adult degeneracy such as witnessed by the police in the instant case.”
In accord is People v. Norton, 1962, 209 Cal.App.2d 173, 25 Cal.Rptr. 676.
In both Young and Norton, the Bielicki and Britt cases, supra are distinguished on the ground that in those cases the toilets were enclosed, whereas in Young and Norton there were no doors on the stalls, so that any member of the public who came in could have seen the offense. We do not decide whether such a distinction is valid. As the District Judge found in this case, it would have been easy for any member of the public to see the offense. Any member of the public could have peered over the door, or the side partitions, or under either, or pushed open the door. We think that, as the Court said in Norton, “If appellant[s] had any right of privacy [they] certainly waived it” (25 Cal.Rptr. at 678).
No case has yet stretched the Fourth Amendment to make its restrictions applicable to a clandestine observation, by officers of the law, of what goes on in a public place. We decline to be the first court to do so, and we think that these stalls were, in essence, a public place. It makes no difference that in this case, as in Norton and Young, the officer was concealed. By using a public place appellants risked observation, and they have no constitutional right to demand that such observation be made only by one whom they could see.
2. While we agree that both the eye and the ear as well as the hand, can “search”, we find here no unreasonable search within the meaning of the Fourth Amendment, as the courts have defined it to date.
On this phase of the matter, the District Judge concluded:
“I do not feel that it was an unreasonable search. Again, I apply it to the facts of this particular case: the doors, the openness, the fact that there had been two complaints in the prior week and one within half an hour just preceding the actual commencement of the search, the fact that almost immediately after Twight took his position in the attic he observed Gunther come in and go out and come in and go out and come back in again, I think that all of this gave the search the necessary degree of reasonability that it could be continued up to the point when finally evidently Mr. Smayda came in and the criminal act was consummated.”
In essence, the court found that the “search” was reasonable. We might not state the matter just as he did, but we, too, think that it was reasonable under the circumstances.
We revert to the specific language of the amendment — “The right of the people to be secure in their persons, houses, papers and effects.” Here was no physical search of appellants’ persons; only observation from a distance, albeit a short one. Here no papers or effects of any kind were discovered or seized. Here, if anything, there was only an invasion, by the eye, of appellants’ “house”, if a public toilet stall can be so called while they occupied it. Appellants point to cases extending the protected area from the ordinary conception of a “house” to such places as the private portion of a business office (Silverthorne Lumber Co. v. United States, 1920, 251 U.S. 385, 40 S.Ct. 182, 64 L.Ed. 319), a locked store, apparently attached to a house (Amos v. United States, 1921, 255 U.S. 313, 41 S.Ct. 266, 65 L.Ed. 654), a private automobile and office (Davis v. United States, 1946, 328 U.S. 582, 66 S.Ct. 1256, 90 L.Ed. 1453 (dictum)), a hotel room (Lustig v. United States, 1949, 338 U.S. 74, 69 S.Ct. 1372, 93 L.Ed. 1819; United States v. Jeffers, 1951, 342 U.S. 48, 72 S.Ct. 93, 96 L.Ed. 59), an apartment (Jones v. United States, 1960, 362 U.S. 257, 80 S.Ct. 725, 4 L.Ed.2d 697), an automobile (Gambino v. United States, 1927, 275 U.S. 310, 4 S.Ct. 137, 72 L.Ed. 293) (treated as an extension of the person), and a taxi (Rios v. United States, 1960, 364 U.S. 253, 80 S.Ct. 1431, 4 L.Ed.2d 1688). Rios and *256Gambino are perhaps most closely analogous — but in those cases there was either a physical search of the car (Gambino) or a seizure of evidence in it (Rios). Surely, if all that were involved were a seeing of what the party did in the car, that would not have been an illegal search, absent some other illegal conduct by the officers.
The essence of appellants’ position is that, while they were in the stalls, those stalls became private places — analogous to their houses — and hence protected from police observation. But even the inspection of the interior of a house, from the outside, and without a trespass by the officers, has never been held to be an unlawful search. The theory is that people who choose to commit crimes where they may be seen take the chance that they will be seen.
If we assume that, when appellants entered the stalls, they then acquired some sort of right, however temporary, to their exclusive occupancy, we think that they acquired that right subject to the condition in which the stalls then were — including not only the spaces above and below the partitions and the doors and the holes in the walls, which they were quite willing to use, but also the holes in the ceiling. No rights of theirs were invaded when the holes were made; they were made by persons who had a right to make them, and at a time when the appellants had no “rights” at all in the stalls. No rights of appellants were invaded when the ranger and photographer went into the attic. No rights of anyone were infringed by their mere presence. All that appellants complain of is that they were seen.
So far, at least, the Supreme Court has not extended the Fourth Amendment to such a situation. In every case, there has been some physical and unconsented to invasion of a private place, the property (either permanent or temporary) of the defendant or of a non-consenting third person. In the case of hotel rooms and apartments, these are so analogous to a home that the Courts treated them in the same way where the amendment has been held to be violated. In each such case, there has been an actual physical invasion — a trespass. Where this has not occurred, the discovery of crime, even by the electronically extended ear, has been upheld. (Goldman v. United States, 1942, 316 U.S. 129, 62 S.Ct. 993, 86 L.Ed. 1322 — detectaphone in adjoining room, On Lee v. United States, 1952, 343 U.S. 747, 72 S.Ct. 967, 96 L.Ed. 1270 — lawful entry — agent wired for sound, Lopez v. United States, 1963, 373 U.S. 427, 83 S.Ct. 1381, 10 L.Ed.2d 462, cf. Lanza v. State of New York, 1962, 370 U.S. 139, 82 S.Ct. 1218, 8 L.Ed.2d 384). We apply the same rule here, to the officer’s eye.
It is asserted that we have here a “general exploratory search,” and that it is therefore unreasonable. The cases relied upon (United States v. Lefkowitz, 1932, 285 U.S. 452, 52 S.Ct. 420, 76 L.Ed. 877; Go-Bart Importing Co. v. United States, 1931, 282 U.S. 344, 51 S.Ct. 153, 75 L.Ed. 374) are different — each involved the physical invasion of private premises, an arrest, and then a general exploratory search of the premises for evidence of crime. Compare Harris v. United States, 1947, 331 U.S. 145, 67 S.Ct. 1098, 91 L.Ed. 1399; United States v. Rabinowitz, 1950, 339 U.S. 56, 70 S.Ct. 430, 94 L.Ed. 653.
To sustain appellants’ contention, we would have to hold that appellants have a right of privacy, protected by the Fourth Amendment, that is so broad that it extends to what they do in a public toilet. That there is a right of privacy, we agree. (McDonald v. United States, 1948, 335 U.S. 451, 69 S.Ct. 191, 93 L.Ed. 153; Brock v. United States, 5 Cir., 1955, 223 F.2d 681; People of State of Cal. v. Hurst, 9 Cir., 1964, 325 F.2d 891, 898, reversed on other grounds, 381 U.S. 760, 85 S.Ct. 1796, 14 L.Ed.2d 713, cf. Griswold v. Connecticut, 1965, 381 U.S. 479, 85 S.Ct. 1678, 14 L.Ed.2d 510; Beaney, “The Constitutional Right to Privacy in the Supreme Court,” The Supreme Court Review, 1962, 212). The question, however, is the extent of that right. (See, generally, Note, 63 *257Columb.L.E. 955, 1963). We agree that every person who enters an enclosed stall in a public toilet is entitled to believe that, while there, he will have at least the modicum of privacy that its design affords. We would not uphold a clandestine surveillance of such an area without cause. We are made as uncomfortable as the next man by the thought that our own legitimate activities in such a place may be spied upon by the police. We also think, however, that the nature of the place, the nature of the criminal activities that can and do occur in it, the ready availability therein of a receptacle for disposing of incriminating evidence, and the right of the public to expect that the police will put a stop to its use as a resort for crime all join to require a reasonable limitation upon the right of privacy involved. We hold that when, as here, the police have reasonable cause to believe that public toilet stalls are being used in the commission of crime, and when, as here, they confine their activities to the times when such crimes are most likely to occur, they are entitled to institute clandestine surveillance, even though they do not have probable cause to believe that the particular persons whom they may thus catch in flagrante delicto have committed or will commit the crime. The public interest in its privacy, we think, must, to that extent, be subordinated to the public interest in law enforcement.
Affirmed.
. “Whoever within or upon any of the places now existing or-hereafter reserved or acquired as provided in section 7 of this title, is guilty of any act or omission which, although not made punishable by any enactment of Congress, would be pun- - ishable if committed or omitted within the jurisdiction of the State, Territory, Possession, or District in which such place is situated, by the laws thereof in force at the time of such act or omission, shall be guilty of a like offense and subject to a like punishment.”
. In Bielieki, the stall was a pay toilet, with a lock; in Britt the door could he locked. The opinions indicate that the enclosure, in each case, was more complete than here. We do not, however, distinguish the cases oh that ground.
. Sharon v. Hill, C.C.D.Cal., 1885, 24 F. 726, 731; People of Puerto Rico v. Shell Co., 1937, 302 U.S. 253, 265-66, 58 S.Ct. 167, 82 L.Ed. 235; United States v. Press Publishing Co., 1911, 219 U.S. 1, 31 S.Ct. 212, 55 L.Ed. 65.
. United States v. Andem, D.C., N.J.1908, 158 F. 996, 1000; McCoy v. Pescor, 8 Cir., 1944, 145 F.2d 260; cf. Johnson v. Yellow Cab Transit Co., 1944, 321 U.S. 383, 388-392, 64 S.Ct. 622, 88 L.Ed. 814; Williams v. United States, 1946, 327 U.S. 711, 66 S.Ct. 778, 90 L.Ed. 962.