opinion: Mr. Justice Harlan
  delivered the opinion of the Court.
  The petitioner, German S. Lopez, was tried in a federal court on a four-count indictment charging him with attempted bribery of an Internal Revenue Agent, Roger S. Davis, in violation of 18 U. S. C. § 201. The questions before us for review are:' (1) whether the trial court’s treatment of “entrapment” constituted reversible error; and (2) whether Davis’ testimony relating to a conversation with petitioner on October 24, 1961, which formed the basis of the three, counts, of the indictment on which petitiofier was convicted, and a wire recording of that conversation^ were properly admitted into evidence.
  The evidence at the trial related to three meetings between Lopez, and Davis that took place at Clauson’s Inn, situated at North Falmouth, Massachusetts, and operated by Lopez under a lease. Davis, who was investigating possible evasion of excise taxes in the area, first visited the Inn on the afternoon of August 31,1961, when he asked.Lopez whether there was any. dancing, singing, or other entertainment in the evenings and showed him an advertisement for the Inn which stated that there was. Lopez said there was no entertainment and denied responsibility for the advertisement. Davis returned again that evening and saw dancing in the bar and lounge. He described the Inn in a report to his superior the next day as a “potential delinquent” and said that he would “follow up.”
  Davis next returned to the Inn on October 21, when he again saw dancing in the bar and lounge, and" spoke with Lopez. • Davis’ testimony about this meeting may be summarized as follows:. Early in the. discussion, Davis told Lopez that he thought the establishment would be liable for a cabaret tax and asked to see the books, but Lopez resisted and suggested that they continue the conversation in his,office. Once there, Lopez suggested that he would like to avoid all “aggravation” and to reach an'“agreement.” After Davis said he could not drop the matter and would return the following' week; Lopez said he didn’t wish to “insult” Davis and that he didn’t know whether to take him into his “confidence.” Receiving no reply, Lopez put some money on the desk saying:
  “You can drop this case. Here’s $200. Buy your wife a present. And I’ll have more money for you at Christmas time. This is all I have now.”
  Davis balked, and Lopez urged him to take the money and to bring his wife and family for a weekend “as my guest.” Following some questioning as to the extent of Lopez’ business, during the course of which Davis estimated a year’s tax as running to $3,000, Lopez added another $220 to the money on the desk, stating that he did not want to be bothered with returns for past years but would file a return, for the current quarter. More importunities on Lopez’ part followed and Davis finally took the money. Before Davis left, Lopez again said he .would file a return for the current quarter and asked Davis to come back, on October 24.
  Lopez, in his version of the events of October 21, admitted giving the $420 to Davis but said the money was given in an effort to have Davis prepare his returns and-get his books in proper order. According to Lopez’ testimony, he told Davis that he would file returns from October 17 on, since on that date the Inn had changed its policy to one of entertainment.
  After leaving the Inn, Davis-reported the meeting to a •fellow agent and to his superior and turned over the $420 to a Regional Inspector. On the morning of October 24, he met with four Internal Revenue Inspectors, who instructed him to keep his appointment with Lopez, to “pretend to play along with the scheme,” and to draw the conversation back to the meeting of October 21. Davis was then equipped with two electronic devices, a pocket battery-operated transmitter, (which subsequently failed to work) and a pocket wiré recorder, which recorded the conversation between. Lopez and Davis at their meeting later in the day.
  According to the recording of that conversation, Davis suggested they talk in Lopez’ office and, once inside the office, Davis started to explain the excise tax form and to discuss the return. Before any computations were made, Lopez said he had never thought he needed to file a cabaret tax return, and the conversation then continued:
  “Lopez: . . . Whatever we decide to do from here on I’d like you to be on my side and visit with me. Deduct anything you think you should and I’ll be happy to . . . because you may prevent something coming up in the office. If you think I should be advised about it let me know. Pick up the phone. I can meet you in town or anywhere you want. For your information the other night I have to . . .
  “Davis: Well, you know I’ve got a job to do.
  “Lopez: Yes, and Uncle Sam'is bigger than you and I are and we pay a lot of taxes, and if we can benefit something by it individually, let’s keep it that way and believe me anything that transpires between you and I, not even my wife or my accountant or anybody is aware of it. So I want you to feel that way about it.”
  The two then discussed receipts and the potential tax liability for 1959-1961, and Lopez protested that Davis’ estimates were very high, although he did not deny the fact' of liability. After Davis said, “I don’t want to get greedy or anything,” Lopez gave him $200 and later in the conversation told Davis he could bring his family down for a free weekend, and should “[c]ome in every so often and I’ll give you a couple of hundred dollars every time you come in.” At one point, Lopez said “Now if you should suggest that T should file returns from this point on, I’ll do it. If you suggest that I can get by without doing it, then just drop in every so often and I’ll . . .” Lopez also confirmed that he had given Davis $420 on October 21.
  Lopez, in his testimony, did not question the accuracy of the recording and in fact said little 'more about the meeting of October 24 than that Davis had goné into a lot of figures and that he (Lopez) had become emotionally upset because he felt that Davis “was not there for the purpose that he came in there fpr on October 21st.” He did not suggest that Davis had induced him to offer any bribes.
  The first of the four counts in the ensuing indictment charged that at the meeting of October 21, Lopez gave Davis the $420 with intent to induce Davis, among other things, “to refrain from making an examination of the books and records relating to'sales and receipts” at the Inn from 1959-1961. The remaining three counts related to the meeting of October 24, and charged three separate acts of attempted bribery, each fpr the purpose of influencing Davis to aid in concealing sales, receipts, and any cabaret tax due for the years 1959-1961. The acts were the giving of $200 to Davis (Count 2), the promise of an additional $200 the following month (Count 3), and the promise of a free weekend for Davis and his family (Count 4).
  Prior to trial, petitioner filed a motion to suppress as evidence the wire recording of the October 24 conversation between Lopez and Davis. After hearing, this motion was denied. At trial, the motion was renewed and again denied, and the recording was received in evidence. Petitioner did not object to the testimony of Agent Davis relating to the October 24 conversation.
  In his charge to the jury, the trial judge emphasized the presumption of innocence and the burden on the Government to establish “every essential element” of the crime beyond a reasonable doubt. He then detailed what these essential .element's were and called particjulár attention to the contrast between the specific intent charged in Count 1 — to prevent an examination of books and records — and the more general-intent charged in the other three counts — to conceal liability for the tax in question. He strongly suggested -that the specific intent alleged in Count 1 had not been established beyond a reasonable doubt.
  Although defense counsel had briefly adverted to the possibility of “entrapment” in'his summation to the jury, he did not request jüdgment of acquittal on that ground. Nor did he request any instruction on the point- or offer at the trial any evidence particularly aimed at such a defense. Nevertheless, the trial judge did. charge on , entrapment. Petitioner made no objection to this •' instruction, or to any'other aspect of the charge.
  The jury acquitted On Count 1 and found petitioner guilty on Counts 2, 3 and 4. • A motion for judgment notwithstanding the verdict “as a matter of law on the evidence” was denied, and petitioner was sentenced to a term of imprisonment for one year.
  Following per curiam affirmance of the conviction by the Court of Appeals for the First Circuit, 305 F. 2d 825, we granted certiorari, 371 U. S. 859, to consider the two questions stated at the outset of this opinion. Supra, pp. 428-429.
  I.
  The defense of entrapment, its meaning, purpose, and application, are problems that have sharply divided this Court on past occasions. See Sorrells v. United States, 287 U. S. 435; Sherman v. United States, 356 U. S. 369; Masciale v. United States, 356 U. S. 386. Whether in the absence of a conclusive showing the defense is for the court or the jury, and whether the controlling standard looks only to the conduct of the Government, or also takes into account the predisposition of the defendant, are among the issues that have been mooted. We need not, however, concern ourselves with any of these questions here, for under any approach, petitioner’s belated claim' of entrapment is insubstantial, and the record fails to show any prejudice that would warrant reversal on this score.
  The conduct with which the defense of entrapment is concerned is the manufacturing of crime by law enforcement officials and their agents. Such conduct, of course, is far different from the permissible stratagems involved in the detection, and prevention of crime. Thus before the issue of entrapment can fairly be said to have been presented in a criminal prosecution there must have been at least some showing of the kind of conduct by government agents which may well have induced the accused to commit the crime charged.
  In the case before us, we think that such a showing has not been made-. ■ It is undisputed .that at the meeting of October 21, petitioner made an unsolicited offer of $420 to Agent Davis; The references to the October 21 offer in the recorded conversation scarcely leave room for doubt that this offer was made for the same general purpose as the bribes offered at the October 24 meeting: to obtain Davis’ assistance in concealing any cabaret tax liability for past and present periods. As to the meeting of October 24, the recording shows that petitioner’s improper overtures began almost at the outset of the discussion, when he stated: “Deduct anything you think you should and I’ll be happy to . . . because 'you may prevent something coming up in the office.” This and similar statements preceded Davis’ computations, and his comment, “I don’t want to get greedy,” on which petitioner so heavily relies. Moreover, we find nothing in the recording as a whole, or in petitioner’s own testimony, to suggest that his conduct on October 24 was instigated by Davis. Upon any reasonable assessment , of the record, it seems manifest that all that Davis was doing was to afford an opportunity for the continuation of a course of criminal conduct, upon which the petitioner had earlier voluntarily embarked, under circumstances susceptible of proof.
  It is therefore evident that, under any theory, entrapment has not been shown as a matter of law. Indeed, the paucity of the showing might well have justified' a refusal, to instruct the jury at all on entrapment. But in any event no request for such an instruction was made, and there was no objection to the instruction given. Under these circumstances, petitioner may not now challenge the form of that instruction. See Fed. Rules Crim. Proc., 30.; Moore v. United States, 262 F. 2d 216; Martinez v. United States, 300 F. 2d 9. Nor was there on this score any such plain error in the charge, affecting substantial rights, as would warrant reversal despite the failure to object. See Féd. Rules Crim. Proc., 52 (b). Since the record does not disclose a sufficient showing that petitioner was induced to offer a'bribe, we cannot conclude that he was prejudiced by the charge on burden of proof, even assuming that the burden called for was too great. By the same token, we are not persuaded that in this case it is significant to determine whether entrapment should turn on the effect of the Government’s conduct on “men of ordinary firmness,” as the court charged, or on the effect on the particular defendant. Accordingly, we do not reach the question whether the charge was in every respect a correct statement of the law. It is enough to say that in the circumstances of this case, there was in any event no reversible error.
  II.
  Petitioner’s remaining contentions concern the admissibility of the evidence relating to his conversation with Davis on October 24. His argument is primarily addressed to the recording of the conversation, which he claims was obtained in violation of his rights under the Fourth Amendment. Recognizing the weakness of this position if Davis was properly permitted to testify about the same conversation, petitioner now challenges that testimony as well, although he failed to do so at the trial. His theory is that, in view of Davis’ alleged falsification of his mission, he gained access to petitioner’s office by misrepresentation and all evidence obtained in the office, i. e., his conversation with petitioner, was illegally “seized.” In support of this theory, he relies on Gouled v. United States, 255 U. S. 298, and Silverman v. United States, 365 U. S. 505. But under the circumstances of the present case, neither of these decisions lends any comfort to petitioner, and indeed their rationale buttresses the conclusion that the evidence was properly admitted. See On Lee v. United States, 343 U. S. 747.
  We need not be long detained by the belated claim that Davis should not have been permitted to testify, about the conversation of October 24. Davis was not guilty of an unlawful invasion of petitioner’s office simply because his apparent willingness to accept a bribe -was not real. Compare Wong Sun v. United States, 371 U. S. 471. He-was in the office with petitioner’s consent, and while there he did not violate the privacy of the office by seizing something surreptitiously without petitioner’s knowledge. Compare Gouled v. United States, supra. The only evidence obtained consisted of statements made by Lopez to Davis, statements which Lopez knew full well could be used against him by Davis if he wished. We decline to hold that whenever an offer of a bribe is made in private, and the offeree does not intend to accept, that offer is a constitutionally protected communication.
  Once it' is plain that Davis could properly, testify about his conversation' with Lopez, the constitutional claim relating to the recording of that conversation emerges in proper perspective. The Court has in the past sustained instances of “electronic eavesdropping’’ against constitutional challenge, when devices have been used to enable government agents to overhear conversations which would have been beyond the reach of the human ear. See, e. g., Olmstedd v. United States, 277 U. S. 438; Goldman v. United States, 316 U. S. 129. It has. been insisted only that the electronic device not be planted by an unlawful physical invasion of a constitutionally protected area. Silverman v. United States, supra. The validity of these decisions is not in question, here. Indeed this case involves no “eavesdropping” whatever in any proper sense of that term. The Government did not use an electronic device to listen in bn conversations it could not otherwise have heard. Instead, the device was used only to obtain the most reliable evidence possible of a conversation in which the Government’s own agent was a participant and which that agent was fully entitled to disclose. And the device was not planted by means of an unlawful physical invasion of petitioner’s premises under circumstances which would violate the Fourth Amendment. It was carried in and out by-an agent who was there with petitioner’s assent, and it neither saw nor heard more than the agent himself.
  The case is thus quite similar to Rathbun v. United States, 355 U. S. 107, in which we sustained against statutory attack the admission in evidence of the testimony of a policeman as to a conversation he overheard on an extension telephone with the consent of a party to the conversation. The present case, if anything, is even clearer, since in Rathbun it was conceded by all concerned “that either party may record the conversation and publish it.” 355 U. S., at 110. (Emphasis added.)
  Stripped to its essentials, petitioner’s argument amounts to saying that he has a constitutional right to rely on possible flaws in the agent’s memory, or to challenge the agent’s credibility without being beset by corroborating evidence that is not susceptible of impeachment. For no other argument can justify excluding an accurate version of a conversation that the agent could testify to from memory. We think the risk that petitioner took in offering a bribe to Davis fairly included the risk that the offer would be accurately reproduced in court, whether by faultless memory or mechanical recording.
  It is urged that whether or not the recording violated petitioner’s constitutional rights, we should prevent its introduction in evidence in this federal trial in the exercise of our supervisory powers. But the court’s inherent power to refuse to receive material evidence is a power that must be sparingly exercised. Its application' in the present case, where there has been no manifestly improper conduct by federal officials, would be wholly unwarranted.
  The function of a criminal trial is to seek out and determine the truth or falsity of the charges brought against the defendant. Proper fulfillment of this function requires that, constitutional limitations aside, all relevant, competent evidence be admissible, unless the manner in which it has been obtained — for example, by violating some statute or rule of procedure — compels the formulation of a rule excluding its introduction in a federal court. See, e. g., McNabb v. United States, 318 U. S. 332; Mallory v. United States, 354 U. S. 449.
  When we look for the overriding considerations that might require the exclusion of the highly useful evidence involved here, we find nothing. There has been no invasion of constitutionally protected rights, and no violation Of federalilaw or rules of procedure. Indeed, there has not even been any electronic eavesdropping on a private conversation which government agents could not otherwise have overheard. There has, in short, been no act of any kind which could justify the creation of an exclusionary rule. We therefore conclude that the judgment of the Court of Appeals must be
  Affirmed.
  18 U. S. C. §201 provides:
  “Whoever promises, offers, or gives any money or thing of value ... to ány officer or employee or person acting for or on behalf of the United States, or any department or agency thereof, in any official function . . . with intent to influence his decision or action on any question,' matter, cause, or proceeding which- may at any time be pending, or which may by law be brought before him in his official capacity, or in his place of trust or profit, or with intent to influence him to commit or aid in committing, or to collude in, .or allow, any fraud, or make.opportunity for the commission of any fraud, on the United States, or to induce him to do or omit to do any act in violation of his lawful duty, shall be fined not more than three times the amount of such money or value of such thing or imprisoned not more than three years, or both.”.
  There have been no omissions from this passage. The indicated elisions appear in the original record.
  Count 1 also charged that the money was given to induce Davis “to refrain . . . from computing a cabaret tax on . . . [the business of the Inn], and from reporting same to the Internal Revenue Service.”
  “Now the law with respect to entrapment is this: if a government agent by improper means or over-bearing persuasion or wrongful conduct induces a person of ordinary firmness to commit a crime which he would not otherwise commit, then under those circumstances the defendant is to be acquitted, not because he did not do something ‘ wrongful but because he was induced to do a wrongful act which he would not otherwise have done.
  “Now needless to say in all types of law enforcement, particularly with respect to matters involving certain types of regulatory statutes, it is often difficult for the government to get evidence, and government agents may properly,- and without violating the law, or their duty, take such steps as make it possible to procure evidence even though such steps involve their own participation, provided that their participation is not a deliberate temptation to men of ordinary firmness, provided that they do not cause a crime to be committed by someone who does not have a criminal disposition to commit that crime.
  “The burden of proof with respect to entrapment is on the defendant. And you are to ask. yourself whether in .fact on the evidence you heard you are persuaded by the preponderance of that evidence that-'Agent Davis, as it were, created the crime and the temptation, and he, Agent Davis, was the instigator and author of a crime that would, never under any circumstances have taken place, had he not used .unfair means.”
  That this was the purpose of the October 21 offer is in no way inconsistent with the verdict of acquittal on Count 1. Count 1, as noted above, charged, among other things, a specific intent to induce the agent not to examine books and records, and the court in its charge attached great emphasis to the language of this count. Thus it may well have been that the acquittal on Count 1 was based solely on the jury’s conclusion that the Government had not proved the existence of the specific intent beyond a reasonable doubt.
  Petitioner claims that Davis’ assertions of the existence of cabaret tax liability, and of the extent of that liability, were so recklessly false as to suggest or require a finding of entrapment. But as noted, petitioner’s overtures preceded these assertions, and in any event, Davis had ample basis for believing that taxes were due, and petitioner never undertook to deny his liability during the conversation on October 24. Although Davis conceded that he may have made some errors in computation because of “nervousness,” petitioner in his testimony made no claim that these computations led to the bribe offers.
  Petitioner does not claim that the issue of entrapment should always be decided by the court and never submitted to the jury, and we are not now presented with that question. See Sherman v. United States, 356 U. S. 369; Masciale v. United States, 356 U. S. 386.
  Rule 30 provides in pertinent part:
  “No party may assign as error any portion of the charge or omission therefrom unless he objects thereto before the jury retires to consider its verdict, stating distinctly the matter to which he objects and the grounds of his objection. Opportunity shall be given to make the objection out of the hearing of the jury.”
  The Fourth Amendment provides: “The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or .affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”
  In On Lee, the defendant had been induced to make certain statements by an old acquaintance who, .without the defendant’s knowledge, had turned government informer and was carrying a small concealed microphone which transmitted the conversation to a narcotics agent some distance away. Thus any differences between On Lee and this case cut against the petitioner.
  The trustworthiness of the recording is not challenged.
  Since Agent Davis himself testified to the conversation with petitioner which was the subject matter of the recording, the question whether there may be circumstances in which the use of such recordings in evidence should be limited to-purposes of “corroboration” is not presented by this case.