This is a direct appeal by defendants-appellants from a conviction for violation of various federal narcotic laws. The defendant, Jesus Martinez, Jr., was convicted under a three count indictment charging sale of heroin without a written prescription (26 U.S.C. § 4705[a]); selling heroin knowing it had been imported into the United States in violation of 21 U.S.C. § 174; and participating in a conspiracy to violate the narcotic laws. The defendant, Tomas Martinez, Jesus Martinez’s brother, and the defendant, Alejandro Handy, were only charged and convicted as being members of the conspiracy. Also named in the indictment as co-conspirators but not as defendants were Jesus Perez and Andres DeLaCerda.
The conspiracy of the defendants was to traffic in heroin in the Toledo, Ohio area, but there is no need to detail the facts of this case. The transcript of the trial establishes that there was sufficient and substantial evidence to support the verdicts of guilty returned by the jury on both the conspiracy and the substantive charges. Our examination of the entire record also reveals that the defendants received a fair trial free of any error affecting their substantial rights and we affirm the judgments of conviction.
Defendant, Jesus Martinez, has raised several issues, three of which attack the validity of his conviction. First, he alleges that the District Court erred in not informing him of his right to separate counsel in a trial for conspiracy. Jesus and his brother Tomas Martinez had privately retained an attorney to act as counsel for both during this trial. In support of his position he relies upon Glasser v. United States, 315 U.S. 60, 62 S.Ct. 457, 86 L.Ed. 680 (1942). Glasser does stand for the general proposition that under certain circumstances an accused person is denied his right to effective assistance of counsel when an attorney defends two accused persons at the same trial. However, the record reveals that defendant has fallen considerably short of making out a case for relief along the lines of Glasser. There, counsel was appointed by the court to serve for another defendant over the objection of Glasser who had originally retained the attorney. In addition, there were numerous incidents which took place at the trial that could be pointed to as indicia of ineffective assistance of counsel directly precipitated by having had one attorney act for the two defendants. The present situation lacks any substantial similarity to Glasser. Here counsel was privately retained by both defendants and no objections were raised before or during trial. Furthermore, defendant has been unable to point to a single incident which indicated a lack of effective assistance of counsel in deprivation of his Sixth Amendment rights.
Another issue raised by Jesus Martinez is two-fold. First, he maintains it was reversible error for the District Court to admit as evidence certain material obtained by monitoring a telephone call made by him and by electric *88“bugging” of his car. Second, he argues his Fourth Amendment rights were violated because the government did not provide its surveillance records for appellant’s examination before the trial. Respecting the contention that the court erred in admitting certain “tainted” evidence, defendant argues that Katz v. United States, 389 U.S. 347, 88 S.Ct. 507, 19 L.Ed.2d 576 (1967), makes evidence obtained by eavesdropping inadmissible. The simple answer to this argument is that Katz is to be applied prospectively, Desist v. United States, 394 U.S. 244, 89 S.Ct. 1030, 22 L.Ed.2d 248 (1968); Linkletter v. Walker, 381 U.S. 618, 85 S.Ct. 1731, 14 L.Ed.2d 601 (1965); United States v. Lucia, 416 F.2d 920 (5th Cir. 1969), and the alleged tainted evidence in this case was obtained before the Katz decision was rendered. However, there is a more basic answer to defendant’s contention, that is, that Katz is not applicable under the facts in this case. In Katz a telephone booth was wired so that a conversation could be overheard without the consent of either party to the conversation. This is distinguishable from the present situation in which one member of the conversation consented to having federal agents listen in on the conversation. This Court has in a similar case held that evidence gathered in this fashion is legally obtained. See United States v. Gardner and Montgomery, 416 F.2d 879 (6th Cir. 1969), but cf. United States v. White, 405 F.2d 838 (7th Cir. 1969), cert. granted 394 U.S. 957, 89 S.Ct. 1305, 22 L.Ed. 2d 559 (1969).
Defendant’s argument that he was denied his Fourth Amendment rights when he was not permitted access to the government’s surveillance records hinges on whether the surveillance evidence was legally obtained. In Alderman v. United States, 394 U.S. 165, 89 S.Ct. 961, 22 L.Ed.2d 176 (1969), the issue was whether certain eavesdropping evidence was legally obtained. To reach a conclusion on this issue the government’s surveillance records were required to be made available for an examination. The present case is outside the rule in Alderman. Here the method of gathering the alleged tainted evidence was admitted. The only purpose for which Alderman permits examination of the surveillance records is to determine whether the method used in gathering evidence was illegal. Defendant knew of the method and could argue the legality of it. There was no violation of defendant’s rights in denying him access to these records.
Finally, Jesus Martinez attacks the constitutionality of the provisions of the narcotic laws under which he was convicted. Specifically, he alleges that the presumption in 21 U.S.C. § 174 that a person in possession of a “narcotic drug” is presumed to know that it was imported contrary to law is unconstitutional as denial of due process, and that the recording and registration provisions of the narcotic laws violate the protection against self-incrimination provided in the Fifth Amendment. The authorities, however, uphold the statute against both constitutional attacks. See Montgomery v. United States, 407 F.2d 1312 (9th Cir. 1969), upholding the statute against attack on the grounds that the registration provisions require self-incrimination; See Turner v. United States, 396 U.S. 398, 90 S.Ct. 642, 24 L.Ed.2d 610 (1970), upholding the presumption that possession of heroin is sufficient to presume that a person knew that the drug was imported illegally.
Tomas Martinez, Jesus’ brother, was convicted of conspiring to violate the narcotic laws. He also makes numerous complaints. Two issues presented are already dealt with, they are (1) the constitutional attack on 21 U.S.C. § 174 and (2) the allegation that because one attorney served as trial counsel for both Jesus and Tomas Martinez they were denied their right to effective assistance of counsel. There are three additional alleged errors which he presents. Defendant, Tomas Martinez, first contends that he was improperly denied the opportunity to impeach his co-conspirator DeLaCerda who testified against him. *89DeLaCerda had stated that while in prison Tomas had offered to introduce him to his brother, Jesus, so arrangements could be made for him to sell narcotics for Jesus when released from prison. The government offered this evidence to show the inception of the conspiracy and Tomas Martinez’s role in it. DeLaCerda was not cross-examined with respect to this conversation. When Tomas took the stand in his own defense, he was not permitted to testify to what DeLaCerda said at the conversation on the grounds that a foundation for impeachment had not been laid. The court stated “you can tell what you said, but you can’t advise the jury of any questions or answers Mr. DeLaCerda put to you.”
Tomas maintains that no foundation need be laid to impeach a witness by contradiction on a material issue in a case. United States v. Klein, 187 F.2d 873 (7th Cir. 1951), cert. denied, 341 U.S. 952, 71 S.Ct. 1021, 95 L.Ed. 1374 (1951); Ewing v. United States, 77 U.S.App.D.C. 14, 135 F.2d 633, (1942), cert. denied, 318 U.S. 776, 63 S.Ct. 829, 87 L.Ed. 1145 (1942). But here there was no proffer of evidence showing that the testimony Tomas wanted to give was going to impeach on a matter material to the case. While the argument is made that since the crime of conspiracy is involved the entire conversation is material, we cannot agree. There could have been any number of matters discussed which were not material to the issue of whether a conspiracy existed and upon which DeLa-Cerda could not have been impeached. Tomas did deny ever having offered to introduce DeLaCerda to his brother so he could sell narcotics. Thus, the jury was given the opportunity to resolve any dispute arising in the testimony on whether or not Tomas was the impetus to, or took part in the conspiracy. On this crucial point Tomas was permitted to contradict DeLaCerda. However, if Tomas was prejudiced by the court’s ruling on this matter, it is not shown in the record because Tomas made no proffer of evidence. Before such an alleged evidentiary error can be reviewed it should, unless it is obvious, be made part of the record. Tanner v. United States, 401 F.2d 281 (8th Cir. 1968), cert. denied, 393 U.S. 1109, 89 S.Ct. 922, 21 L.Ed. 2d 806 (1968); Washington v. United States, 130 U.S.App.D.C. 374, 401 F.2d 915, 921, n. 31 (1968).
Tomas also argues it was error not to grant him a severance and a separate trial. The record shows that the District Court did not abuse its discretion in not granting separate trials, nor was defendant prejudiced. See Federal Rules of Criminal Procedure, Rule 14; United States v. Armel, 384 F.2d 51 (6th Cir. 1967); United States v. McKinney, 379 F.2d 259 (6th Cir. 1967).
It is also alleged to have been error for the District Court not to permit defendant, Tomas Martinez, the right to examine portions of the grand jury proceedings. Since there was no record made of the grand jury proceedings such a request, even if proper, could not have been granted.
Our review of the transcript also shows that, while the evidence to convict Tomas Martinez may have been quantitatively small, in terms of qualitative sufficiency, it was more than adequate.
Defendant, Alejandro Handy, also presents several issues for review. For the same reasons discussed above with respect to Tomas Martinez’s identical contention, no error was committed in denying defendant, Handy, a separate trial. The other objection raised by defendant, Handy, requiring comment is that error was committed in admitting into evidence various exhibits which did not pertain to the charges against him. These exhibits were introduced as evidence in the government’s case in chief against the other defendants. Whenever there is more than one defendant standing trial at the same time, it is inevitable that there will be introduced evidence which does not affect all the defendants. While there are situations in which this could prejudice the defend*90ants not affected by the evidence, here the jury was carefully instructed and no prejudice against the defendant occurred.
Affirmed.