Mr. Justice Powell
delivered the opinion of the Court.
Respondent was convicted of possessing an unregistered still, carrying on the business of a distiller without giving bond and with intent to defraud the Government of whiskey tax, possessing 175 gallons of whiskey upon which no taxes had been paid, and conspiring to defraud the United States of tax revenues. 26 U. S. C. §§ 5179, 5205, 5601 et seq.; 18 U. S. C. § 371. Prior to trial respondent moved to suppress copies of checks and other bank records obtained by means of allegedly defective subpoenas duces tecum served upon two banks at which he had accounts. The records had been maintained by the banks in compliance with the requirements of the Bank Secrecy Act of 1970, 84 Stat. 1114, 12 U. S. C. § 1829b (d).
The District Court overruled respondent’s motion to suppress, and the evidence was admitted. The Court of Appeals for the Fifth Circuit reversed on the ground that a depositor’s Fourth Amendment rights are violated when bank records maintained pursuant to the Bank Secrecy Act are obtained by means of a defective subpoena. It held that any evidence so obtained must be suppressed. Since we find that respondent had no pro-tectable Fourth Amendment interest in the subpoenaed documents, we reverse the decision below.
I
On December 18, 1972, in response to an informant’s tip, a deputy sheriff from Houston County, Ga., stopped a van-type truck occupied by two of respondent’s alleged co-conspirators. The truck contained distillery apparatus and raw material. On January 9, 1973, a fire broke out in a Kathleen, Ga., warehouse rented to respondent. During the blaze firemen and sheriff department officials discovered a 7,500-gallon-eapacity distillery, 175 gallons of non-tax-paid whiskey, and related paraphernalia.
Two weeks later agents from the Treasury Department’s Alcohol, Tobacco and Firearms Bureau presented grand jury subpoenas issued in blank by the clerk of the District Court, and completed by the United States Attorney’s office, to the presidents of the Citizens & Southern National Bank of Warner Robins and the Bank of Byron, where respondent maintained accounts. The subpoenas required the two presidents to appear on January 24, 1973, and to produce
“all records of accounts, i. e., savings, checking, loan or otherwise, in the name of Mr. Mitch Miller [respondent], 3859 Mathis Street, Macon, Ga. and/or Mitch Miller Associates, 100 Executive Terrace, Warner Robins, Ga., from October 1, 1972, through the present date [January 22, 1973, in the case of the Bank of Byron, and January 23, 1973, in the case of the Citizens & Southern National Bank of Warner Robins]
The banks did not advise respondent that the subpoenas had been served but ordered their employees to make the records available and to provide copies .of any documents the agents desired. At the Bank of Byron, an agent was shown microfilm records of the relevant account and provided with copies of one deposit slip and one or two checks. At the Citizens & Southern National Bank microfilm records also were shown to the agent, and he was given copies-of the records of respondent's account during the applicable period. These included all checks, deposit slips, two financial statements, and three monthly statements. The bank presidents were then told that it would not be necessary to appear in person before the grand jury.
The grand jury met on February 12, 1973, 19 days after the return date on the subpoenas. Respondent and four others were indicted. The overt acts alleged to have been committed in furtherance of the conspiracy included three financial transactions — the rental by respondent of the van-type truck, the purchase by respondent of radio equipment, and the purchase by respondent of a quantity of sheet metal and metal pipe. The record does not indicate whether any of the bank records were in fact presented to the grand jury. They were used in the investigation and provided “one or two" investigatory leads. Copies of the checks also were introduced at trial to establish the overt acts described above.
In his motion to suppress, denied by the District Court, respondent contended that the bank documents were illegally seized. It was urged that the subpoenas were defective because they were issued by the United States Attorney rather than a court, no return was made to a court, and the subpoenas were returnable on a date when the grand jury was not in session. The Court of Appeals reversed. 500 F. 2d 751 (1974). Citing the prohibition in Boyd v. United States, 116 U. S. 616, 622 (1886), against “compulsory production of a man’s private papers to establish a criminal charge against him,” the court held that the Government had improperly circumvented Boyd’s protections of respondent’s Fourth Amendment right against “unreasonable searches and seizures” by “first requiring a third party bank to copy all of its depositors’ personal checks and then, with an improper invocation of legal process, calling upon the bank to allow inspection and reproduction of those copies.” 500 F. 2d, at 757. The court acknowledged that the recordkeeping requirements of the Bank Secrecy Act had been held to be constitutional on their face in California Bankers Assn. v. Shultz, 416 U. S. 21 (1974), but noted that access to the records was to be controlled by “existing legal process.” See id., at 52. The subpoenas issued here were found not to constitute adequate “legal process.” The fact that the bank officers cooperated voluntarily was found to be irrelevant, for “he whose rights are threatened by the improper disclosure here was a bank depositor, not a bank official.” 500 F. 2d, at 758.
The Government contends that the Court of Appeals erred in three respects: (i) in finding that respondent had the Fourth Amendment interest necessary to entitle him to challenge the validity of the subpoenas duces tecum through his motion to suppress; (ii) in holding that the subpoenas were defective; and (iii) in determining that suppression of the evidence obtained was the appropriate remedy if a constitutional violation did take place.
We find that there was no intrusion into any area in which respondent had a protected Fourth Amendment interest and that the District Court therefore correctly denied respondent’s motion to suppress. Because we reverse the decision of the Court of Appeals on that ground alone, we do not reach the Government’s latter two contentions.
II
In Hoffa v. United States, 385 U. S. 293, 301-302 (1966), the Court said that “no interest legitimately protected by the Fourth Amendment” is implicated by governmental investigative activities unless there is an intrusion into a zone of privacy, into “the security a man relies upon when he places himself or his property within a constitutionally protected area.” The Court of Appeals, as noted above, assumed that respondent had the necessary Fourth Amendment interest, pointing to the language in Boyd v. United States, supra, at 622, which describes that Amendment’s protection against the “compulsory production of a man’s private papers.” We think that the Court of Appeals erred in finding the subpoenaed documents to fall within a protected zone of privacy.
On their face, the documents subpoenaed here are not respondent’s “private papers.” Unlike the claimant in Boyd, respondent can assert neither ownership nor possession. Instead, these are the business records of the banks. As we said in California Bankers Assn. v. Shultz, supra, at 48-49, “[blanks are . . . not . . . neutrals in transactions involving negotiable instruments, but parties to the instruments with a substantial stake in their continued availability and acceptance.” The records of respondent’s accounts, like “all of the records [which are required to be kept pursuant to the Bank Secrecy Act,] pertain to transactions to which the bank was itself a party.” Id., at 52.
Respondent argues, however, that the Bank Secrecy Act introduces a factor that makes the subpoena in this case the functional equivalent of a search and seizure of the depositor’s “private papers.” We have held, in California Bankers Assn. v. Shultz, supra, at 54, that the mere maintenance of records pursuant to the requirements of the Act “invade [s] no Fourth Amendment right of any depositor.” But respondent contends that the combination of the recordkeeping requirements of the Act and the issuance of a subpoena to obtain those records permits the Government to circumvent the requirements of the Fourth Amendment by allowing it to obtain a depositor’s private records without complying with the legal requirements that would be applicable had it proceeded against him directly. Therefore, we must address the question whether the compulsion embodied in the Bank Secrecy Act as exercised in this case creates a Fourth Amendment interest in the depositor where none existed before. This question was expressly reserved in California Bankers Assn., supra, at 53-54, and n. 24.
Respondent urges that he has a Fourth Amendment interest in the records kept by the banks because they are merely copies of personal records that were made available to the banks for a limited purpose and in which he has a reasonable expectation of privacy. He relies on this Court’s statement in Katz v. United States, 389 U. S. 347, 353 (1967), quoting Warden v. Hayden, 387 U. S. 294, 304 (1967), that “we have . . . departed from the narrow view” that “ 'property interests control the right of the Government to search and seize,’ ” and that a “search and seizure” become unreasonable when the Government’s activities violate “the privacy upon which [a person] justifiably reliefs].” But in Katz the Court also stressed that “[w]hat a person knowingly exposes to the public ... is not a subject of Fourth Amendment protection.” 389 U. S., at 351. We must examine the nature of the particular documents sought to be protected in order to determine whether there is a legitimate “expectation of privacy” concerning their contents. Cf. Couch v. United States, 409 U. S. 322, 335 (1973).
Even if we direct our attention to the original checks and deposit slips, rather than to the microfilm copies actually viewed and obtained by means of the subpoena, we perceive no legitimate “expectation of privacy” in their contents. The checks are not confidential communications but negotiable instruments to be used in commercial transactions. All of the documents obtained, including financial statements and deposit slips, contain only information voluntarily conveyed to the banks and exposed to their employees in the ordinary course of business. The lack of any legitimate expectation of privacy concerning the information kept in bank records was assumed by Congress in enacting the Bank Secrecy Act, the expressed purpose of which is to require records to be maintained because they “have a high degree of usefulness in criminal, tax, and regulatory investigations and proceedings.” 12 U. S. C. § 1829b (a) (1). Cf. Couch v. United States, supra, at 335.
The depositor takes the risk, in revealing his affairs to another, that the information will be conveyed by that person to the Government. United States v. White, 401 U. S. 745, 751-752 (1971). This Court has held repeatedly that the Fourth Amendment does not prohibit the obtaining of information revealed to a third party and conveyed by him to Government authorities, even if the information is revealed on the assumption that it will be used only for a limited purpose and the confidence placed in the third party will not be betrayed. Id., at 752; Hoffa v. United States, 385 U. S., at 302; Lopez v. United States, 373 U. S. 427 (1963).
This analysis is not changed by the mandate of the Bank Secrecy Act that records of depositors' transactions be maintained by banks. In California Bankers Assn. v. Shultz, 416 U. S., at 52-53, we rejected the contention that banks, when keeping records of their depositors' transactions pursuant to the Act, are acting solely as agents of the Government. But, even if the banks could be said to have been acting solely as Government agents in transcribing the necessary information and complying without protest with the requirements of the subpoenas, there would be no intrusion upon the depositors' Fourth Amendment rights. See Osborn v. United States, 385 U. S. 323 (1966); Lewis v. United States, 385 U. S. 206 (1966).
Ill
Since no Fourth Amendment interests of the depositor are implicated here, this case is governed by the general rule that the issuance of a subpoena to a third party to obtain the records of that party does not violate the rights of a defendant, even if a criminal prosecution is contemplated at the time the subpoena is issued. California Bankers Assn. v. Shultz, supra, at 53; Donaldson v. United States, 400 U. S. 517, 537 (1971) (Douglas, J., concurring). Under these principles, it was firmly settled, before the passage of the Bank Secrecy Act, that an Internal Revenue Service summons directed to a third-party bank does not violate the Fourth Amendment rights of a depositor under investigation. See First National Bank of Mobile v. United States, 267 U. S. 576 (1925), aff’g 295 F. 142 (SD Ala. 1924). See also California Bankers Assn. v. Shultz, supra, at 53; Donaldson v. United States, supra, at 522.
Many banks traditionally kept permanent records of their depositors’ accounts, although not all banks did so and the practice was declining in recent years. By requiring that such records be kept by all banks, the Bank Secrecy Act is not a novel means designed to circumvent established Fourth Amendment rights. It is merely an attempt to facilitate the use of a proper and longstanding law enforcement technique by insuring that records are available when they are needed.
We hold that the District Court correctly denied respondent’s motion to suppress, since he possessed no Fourth Amendment interest that could be vindicated by a challenge to the subpoenas.
IV
Respondent contends not only that the subpoenas duces tecum directed against the banks infringed his Fourth Amendment rights, but that a subpoena issued to a bank to obtain records maintained pursuant to the Act is subject to more stringent Fourth Amendment requirements than is the ordinary subpoena. In making this assertion he relies on our statement in California Bankers Assn., supra, at 52, that access to the records maintained by banks under the Act is to be controlled by "existing legal process.”
In Oklahoma Press Pub. Co. v. Walling, 327 U. S. 186, 208 (1946), the Court said that “the Fourth [Amendment], if applicable [to subpoenas for the production of business records and papers], at the most guards against abuse only by way of too much indefiniteness or breadth in the things required to be 'particularly described,’ if also the inquiry is one the demanding agency is authorized by law to make and the materials specified are relevant.” See also United States v. Dionisio, 410 U. S. 1, 11-12 (1973). Respondent, citing United States v. United States District Court, 407 U. S. 297 (1972), in which we discussed the application of the warrant requirements of the Fourth Amendment to domestic security surveillance through electronic eavesdropping, suggests that greater judicial scrutiny, equivalent to that required for a search warrant, is necessary when a subpoena is to be used to obtain bank records of a depositor’s account. But in California Bankers Assn., 416 U. S., at 52, we emphasized only that access to the records was to be in accordance with “existing legal process.” There was no indication that a new rule was to be devised, or that the traditional distinction between a search warrant and a subpoena would not be recognized.
In any event, for the reasons stated above, we hold that respondent lacks the requisite Fourth Amendment interest to challenge the validity of the subpoenas.
V
The judgment of the Court of Appeals is reversed. The court deferred decision on whether the trial court had improperly overruled respondent’s motion to suppress distillery apparatus and raw material seized from a rented truck. We remand for disposition of that issue.
So ordered.
The Fourth Amendment implications of Boyd as it applies to subpoenas duces tecum have been undercut by more recent cases. Fisher v. United States, ante, at 407-409. See infra, at 445-446.
Respondent appears to contend that a depositor’s Fourth Amendment interest comes into play only when a defective subpoena is used to obtain records kept pursuant to the Act. We see no reason why the existence of a Fourth Amendment interest turns on whether the subpoena is defective. Therefore, we do not limit our consideration to the situation in which there is an alleged defect in the subpoena served on the bank.
It is not clear whether respondent refers to attempts to obtain private documents through a subpoena issued directly to the depositor or through a search pursuant to a warrant. The question whether personal business records may be seized pursuant to a valid warrant is before this Court in No. 74-1646, Andresen v. Maryland, cert. granted, 423 U. S. 822.
We do not address here the question of evidentiary privileges, such as that protecting communications between an attorney and his client. Cf. Fisher v. United States, ante, at 403-405.
Nor did the banks notify respondent, a neglect without legal consequences here, however unattractive it may be.
Respondent does not contend that the subpoenas infringed upon his First Amendment rights. There was no blanket reporting requirement of the sort we addressed in Buckley v. Valeo, 424 U. S. 1, 60-84 (1976), nor any allegation of an improper inquiry into protected associational activities of the sort presented in Eastland v. United States Servicemen’s Fund, 421 U. S. 491 (1975).
We are not confronted with a situation in which the Government, through “unreviewed executive discretion,” has made a wide-ranging inquiry that unnecessarily "touch[es] upon intimate areas of an individual’s personal affairs.” California Bankers Assn. v. Shultz, 416 U. S., at 78-79 (Powell, J., concurring). Here the Government has exercised its powers through narrowly directed subpoenas duces tecum subject to the legal restraints attendant to such process. See Part IV, infra.
This case differs from Burrows v. Superior Court, 13 Cal. 3d 238, 529 P. 2d 590 (1974), relied on by Mr. Justice Brennan in dissent, in that the bank records of respondent’s accounts were furnished in response to “compulsion by legal process” in the form of subpoenas duces tecum. The court in Burrows found it “significant . . . that the bank [in that case) provided the statements to the police in response to an informal oral request for information.” Id., at 243, 529 P. 2d, at 593.
A subpoena duces tecum issued to obtain records is subject to nó more stringent Fourth Amendment requirements than is the ordinary subpoena. A search warrant, in contrast, is issuable only pursuant to prior judicial approval and authorizes Government officers to seize evidence without requiring enforcement through the courts. See United States v. Dionisio, 410 U. S. 1, 9-10 (1973).
There is no occasion for us to address whether the subpoenas complied with the requirements outlined in Oklahoma Press Pub. Co. v. Walling, 327 U. S. 186 (1946). The banks upon which they were served did not contest their validity.