concurring.
A few words in amplification of this per curiam opinion may help to avoid misunderstanding on the part of the litigants, and of the District Courts to which these cases are remanded.
As we made explicit in Alderman, Butenko, and Ivanov, the requirement that certain products of governmental electronic surveillance be turned over to defense counsel was expressly limited to situations where the surveillance had violated the Fourth Amendment. We did not decide in those cases, and we do not decide in these, that any of the surveillances did violate the Fourth Amendment.1 *314Instead, we have left that threshold question for the District Courts to decide in all these cases.
Moreover, we did not in Alderman, Butenko, or Ivanov, and we do not today, specify the procedure that the District Courts are to follow in making this preliminary determination. We have nowhere indicated that this determination cannot appropriately be made in ex parte, in camera proceedings. “Nothing in Alderman v. United States, Ivanov v. United States, or Butenko v. United States, ante, p. 165, requires an adversary proceeding and full disclosure for resolution of every issue raised by an electronic surveillance.” Taglianetti v. United States, post, p. 316.
Finally, the Court has not in any of these cases addressed itself to the standards governing the constitutionality of electronic surveillance relating to the gathering of foreign intelligence information — necessary for the conduct of international affairs, and for the protection of national defense secrets and installations from foreign espionage and sabotage. Mr. Justice White *315has elsewhere made clear his view that such surveillance does not violate the Fourth Amendment, “if the President of the United States or his chief legal officer, the Attorney General, has considered the requirements of national security and authorized electronic surveillance as reasonable.” 2 While two members of the Court have indicated disagreement with that view,3 the issue remains open.4
One might suppose that all of this should be entirely clear to any careful reader of the Court’s opinion in Alderman, Butenko, and Ivanov. Perhaps so, and perhaps, therefore, what I have said is quite unnecessary. But 10 years of experience here have taught me that the most carefully written opinions are not always carefully read — even by those most directly concerned.
In oral argument of the Butenko and Ivanov cases, the Solicitor General, mystifyingly, sought to concede that the surveillances there were in fact unconstitutional, although he was repeatedly invited *314to argue that they were not. The following colloquies during oral argument of the Ivanov case are illustrative:
“Q. Are you asking us to decide- here or to leave open on remand the question as to whether this violates, this bugging in this particular case, violates the Fourth Amendment?
“A. Our position would be the same had it or not. We are not arguing that it did not violate the Fourth Amendment.
“Q. In other words, the premise in which you are proceeding here is that you admit for the purposes of this case that this was illegal bugging?
“A. Yes, Mr. Justice.
“Q. And you are going to remain free to argue to the district judge that there was no violation?
“A. No, sir.”
In deciding those cases, the Court declined to accept the Solicitor General’s proffered concession.
Katz v. United States, 389 U. S. 347, 364 (White, J., concurring).
Id., at 359 (Douglas, J., concurring).
See id., at 358, n. 23.