(concurring in part and dissenting in part).
The government’s appeal from Judge McMillen’s suppression order requires us to construe (a) an earlier order entered by Judge Campbell authorizing the telephone intercepts and (b) the statutory requirement that such an order specify the identity of the persons, “if known,” whose conversations are to be intercepted. I agree with Judge Kiley that conversations between Minnie and her husband in aid of their criminal enterprise were not privileged. I believe, however, that Judge Campbell’s order of March 20, 1970, authorized the agents to listen to conversations in which Irving did not participate, and that the failure to name Minnie in the order is not an appropriate ground for suppressing her conversations.
A. The Order.
On March 20, 1970, the government applied to Judge Campbell for an order authorizing the interception of conversations using two telephones identified by number and by location in Irving Kahn’s *199residence. One purpose of the request was to intercept communications which would reveal the identity of Irving Kahn’s confederates.1
The request was supported by a detailed 18-page affidavit summarizing the results of a thorough investigation leading to the conclusion that Irving Kahn’s two telephones were being used in an illegal gambling enterprise, and that Irving Kahn was a principal in the venture. Based on that showing, Judge Campbell found probable cause to believe that Irving Kahn “and others as yet unknown” have committed and are committing the specified offenses, and that the two designated telephones “have been and are being used by Irving Kahn and others as yet unknown in connection with the commission of the above described offenses.” It should be noted that he did not find merely that the telephone numbers were being used illegally, but rather that the two telephones in Irving’s residence were being so used by “others as yet unknown” as well as by Irving. Although the record support for Judge Campbell’s findings has been suppressed, it was available to Judge McMillen, who entered the suppression order, as well as to this court. No judge who has reviewed that record has expressed any doubt that Judge Campbell’s findings were fully supported by the record.
Having made the findings required by the statute, Judge Campbell authorized the interception of communications over Irving Kahn’s two telephones. The scope of the authorization granted by Judge Campbell’s order was to “intercept wire communications of Irving Kahn and others as yet unknown concerning the above-described offenses to and from two telephones, subscribed to by Irving Kahn, both located at 9126 Four Winds Way, Skokie, Illinois, a private residence, and carrying telephone numbers 675-9125 and 675-9126, respectively.”
If we consider the language used by Judge Campbell in his findings and in his order, it is clear that the intercept authority was not limited to conversations to which Irving Kahn was a party. If that had been Judge Campbell’s purpose, there would have been no need to refer to the illegal use of the two telephones in Kahn’s residence, not only by Kahn himself, but also by “others as yet unknown.” The authorization in the order does not describe communications between Irving Kahn and others; rather it describes “conversations of Irving Kahn and others as yet unknown” using the two telephones in his residence. If only the conversations of Irving were involved, the findings and the order are replete with redundancies.
My reading of the statement of purpose in the government’s application, Judge Campbell’s findings, and the language of the order itself does not permit me to accept an interpretation which limits the scope of the intercept authority to conversations to which Irving Kahn was a party.
B. The Statute.
There are two separate reasons why I believe the majority misreads the statute: (1) in my opinion the record does not support the conclusion that Minnie Kahn’s participation in the gambling enterprise was “known” to the government on March 20, 1970, within the meaning of § 2518(4)(a); and (2) the adequacy of the government’s investigation prior to March 20, 1970, is not relevant to the “if known” issue arising under § 2518(4)(a), but rather pertains to a question which was resolved by a finding of fact entered in compliance with § 2518(3) (c).
1. Section 2518(b)(a).
This section provides:
“(4) Each order authorizing or approving the interception of any wire or oral communication shall specify—
*200“(a) the identity of the person, if known, whose communications are to be intercepted; . . . ”
82 Stat. 219, 18 U.S.C. § 2518(4)(a).
Just as a search warrant must carefully limit the discretion of the officer executing the warrant by defining the scope of his authority to search and the objects to be seized, this subsection was intended to require the order to define the scope of the agent’s authority to intercept conversations.2 The inclusion of the words “if known” indicates that Congress intended to permit the interception of some conversations of persons whose participation in the criminal activity was unknown at the time the order was entered. As I read the record, Minnie Kahn was such a person on March 20, 1970.
The court does not hold that the record supports the conclusion that Minnie Kahn was a person who was actually “known” to be participating in the conversations sought to be seized. On the contrary, the court treats the statutory words “if known” as if Congress had used language broad enough “to embrace persons whom careful investigation by the government would disclose were probably using the Kahn telephones in conversations for illegal activities.” In my opinion we should adhere to the language which Congress actually used rather than adopt what we might consider to be a more desirable requirement.
The extent of the government’s knowledge should, I believe, be appraised as of the time it requested an intercept order. Just as evidence obtained by means of a search may not be used retroactively to establish probable cause for the issuance of a warrant defective on its face, it seems equally clear that our present knowledge of Minnie Kahn’s guilt may not be imputed to the agents who had not yet intercepted her conversations. If we put the seized evidence to one side, there is nothing in the record to support an inference that the government should have known that Minnie Kahn, instead of Pamela Kahn, Howard Kahn, or possibly some regular visitor, would use Irving’s telephones to transmit gambling information to a third party while he was out of town.
As Judge Kiley points out, it is entirely possible that one of the anonymous informants referred to in the affidavit supporting the government’s application for intercept authority might have known that Minnie made illegal telephone calls and might have given that information to a government investigator; on the other hand, it is also possible that she made such calls only on rare occasions when Irving was out of town, or that informants willing to describe Irving might not have been willing to mention Minnie. The whole inquiry, in my opinion, is a matter of speculation and is neither necessary nor appropriate to the determination of whether the order meets the “if known” requirement of § 2518(4) (a).
2. Section 2518(8) (c).
The statute authorizes the judge to enter an intercept order if he makes certain determinations on the basis of the government’s factual showing. Among others, he must determine that “normal investigative procedures have been tried and have failed or reasonably appear to be unlikely to succeed if tried or to Be too dangerous.” 82 Stat. 219, 18 U.S.C. § 2518(3)(c).
Judge Campbell made an express finding of fact complying with this requirement. The finding is supported by a detailed description of the “normal investi*201gative procedures” which had been used, and by a perfectly reasonable explanation of why “the interception of these telephone communications is the only available method of investigation which has a reasonable likelihood of securing the evidence necessary to prove violations of these statutes.” 3 Although the results of the investigation plainly indicated that Irving Kahn’s telephones were being used in connection with the commission of an offense, the record also supports the conclusion that it was unlikely that admissible evidence would be available to prove Kahn’s guilt unless intercept authority was obtained. Nothing in the record suggests that a further investigation which might have ascertained Minnie’s participation would have obviated the need for such authority. In short, the finding required by § 2518(3) (c) was made and, in my opinion, is supported by the record.
Although § 2518(3) (c) imposes a duty on the government to exhaust normal investigative procedures before applying for an intercept order, it seems unlikely that the “if known” 'requirement in § 2518(4) (a) was intended to impose either an additional exhaustion requirement or a more severe standard for measuring the government’s compliance with the express language of subsection (3)(c). I am therefore persuaded that the majority’s interpretation of the “if known” requirement will merely tend to confuse two quite different statutory purposes.
In sum, in my opinion the court’s decision is predicated on an improper reading of Judge Campbell’s order of March 20, 1970, and an incorrect interpretation of the statute. In view of the majority’s disposition of the case, comment on constitutional issues is inappropriate.
. Affidavit of Douglas P. Boiler, p. 4.
. At least that is a fair inference to be drawn from the language of the section and the explanatory reference in the Senate Committee Report to West v. Cabell, 153 U.S. 78, see especially 87-88, 14 S.Ct. 752, 38 L.Ed. 643, U.S.Code Cong. & Ad.News, 1968, 90th Cong., 2d Sess. p. 2191 (1968).
. Affidavit of Ray I. Shryock, p. 16.