dissenting.
The question before the Court is whether the helicopter surveillance over Riley’s property constituted a “search” within the meaning of the Fourth Amendment. Like Justice Brennan, Justice Marshall, Justice Stevens, and Justice O’Connor, I believe that answering this question depends upon whether Riley has a “reasonable expectation of privacy” that no such surveillance would occur, and does not depend upon the fact that the helicopter was flying at a lawful altitude under FAA regulations. A majority of this Court thus agrees to at least this much.
The inquiry then becomes how to determine whether Riley’s expectation was a reasonable one. Justice Brennan, the two Justices who have joined him, and Justice O’Con-nor all believe that the reasonableness of Riley’s expectation depends, in large measure, on the frequency of nonpolice helicopter flights at an altitude of 400 feet. Again, I agree.
How is this factual issue to be decided? Justice Brennan suggests that we may resolve it ourselves without any evidence in the record on this point. I am wary of this approach. While I, too, suspect that for most American communities it is a rare event when nonpolice helicopters fly over one’s curtilage at an altitude of 400 feet, I am not convinced that we should establish a per se rule for the entire Nation based on judicial suspicion alone. See Coffin, Judicial Balancing, 63 N. Y. U. L. Rev. 16, 37 (1988).
But we need not abandon our judicial intuition entirely. The opinions of both Justice Brennan and Justice O’Con-nor, by their use of “cf.” citations, implicitly recognize that none of our prior decisions tells us who has the burden of proving whether Riley’s expectation of privacy was reasonable. In the absence of precedent on the point, it is appropriate for us to take into account our estimation of the *468frequency of nonpolice helicopter flights. See 4 W. LaFave, Search and Seizure § 11.2(b), p. 228 (2d ed. 1987) (burdens of proof relevant to Fourth Amendment issues may be based on a judicial estimate of the probabilities involved). Thus, because I believe that private helicopters rarely fly over curtilages at an altitude of 400 feet, I would impose upon the prosecution the burden of proving contrary facts necessary to show that Riley lacked a reasonable expectation of privacy. Indeed, I would establish this burden of proof for any helicopter surveillance case in which the flight occurred below 1,000 feet — in other words, for any aerial surveillance case not governed by the Court’s decision in California v. Ciraolo, 476 U. S. 207 (1986).
In this case, the prosecution did not meet this burden of proof, as Justice Brennan notes. This failure should compel a finding that a Fourth Amendment search occurred. But because our prior cases gave the parties little guidance on the burden of proof issue, I would remand this case to allow the prosecution an opportunity to meet this burden.
The order of this Court, however, is not to remand the case in this manner. Rather, because Justice O’Connor would impose the burden of proof on Riley and because she would not allow Riley an opportunity to meet this burden, she joins the plurality’s view that no Fourth Amendment search occurred. The judgment of the Court, therefore, is to reverse outright on the Fourth Amendment issue. Accordingly, for the reasons set forth above, I respectfully dissent.