This case presents the question whether federal law prohibits the use of silent video surveillance as part of a domestic criminal investigation, and if not, what standards govern such surveillance. On an interlocutory appeal brought under 18 U.S.C. § 3731 (1988), a divided panel of this court held domestic silent video surveillance was permitted, but only if processed and approved pursuant to the technical procedures specified in 18 U.S.C. §§ 2510-2521 (1988 & Supp. II 1990) (“Title I”). United States v. Koyomejian, 946 F.2d 1450 (9th Cir.1991), amended on other grounds (9th Cir. Jan. 16, 1992). We granted a rehearing en banc, 957 F.2d 636 (9th Cir.1992), and now hold that silent domestic video surveillance is neither prohibited nor regulated by Title I.
I FACTS
In January of 1988, the government began investigating the conduct of the defendants in this case, Wanis Koyomejian and eighteen other persons, all associated with Ropex Corporation, a gold and jewelry business located in Los Angeles, California.' The government suspected Ropex was being used to launder cash receipts from narcotics trafficking. According to the indictments filed in this case, Koyomejian and his employees would collect the cash received from narcotics sales, deposit it in bank accounts in Los Angeles, and wire *538transfer it to a gold refining company in Florida, supposedly to buy gold for Ropex. From Florida, the money would flow through a series of complex sham transactions, and eventually would be funneled out of the country to companies owned by Colombian drug dealers. The indictments allege that over a two-year period, more than 312 million dollars was laundered by the defendants.
On September 9, 1988, the government filed in district court applications to install hidden microphones and silent closed circuit television cameras inside Ropex’s offices. The application to install the hidden television cameras was brought under Rules 41(b) and 57 of the Federal Rules of Criminal Procedure, and the All Writs Act, 28 U.S.C. § 1651 (1988). The application to install the hidden microphones was brought under Title I. Both applications were supported by a single seventy-seven page affidavit from Bruce R. Stephens, a Special Agent of the Federal Bureau of Investigation.
The district court granted the government’s applications, and on September 19, 1988, the government began both audio and silent video surveillance of Ropex’s offices. The surveillance produced silent video tapes of nine of the defendants receiving, counting, and packaging large amounts of cash, which later was deposited into local banks. On February 22, 1989, the defendants were arrested and all surveillance ceased.
On March 7, 1989, the defendants were indicted for conspiracy to aid and abet the possession and distribution of cocaine, in violation of 21 U.S.C. §§ 841(a)(1), 846 (1988), 18 U.S.C. § 2 (1988), and conspiracy to launder monetary instruments, in violation of 18 U.S.C. §§ 371, 1956 (1988), as well as substantive money laundering counts, in violation of 18 U.S.C. § 1956. Seven of the nineteen defendants pleaded guilty. The remaining twelve defendants, eleven of whom were the subject of a superseding indictment, are the appellants in this case.
Throughout March of 1990, the district court held hearings on various pretrial motions filed by the defendants, including a motion to suppress the fruits of the video surveillance. On March 27, 1990, the district court ruled that domestic silent video surveillance was prohibited by Title I, and granted the defendants’ motion to suppress. The district court denied the government’s motion for reconsideration, but stayed the trial pending the government’s interlocutory appeal to this court.
II DISCUSSION
This case hinges on a proper interpretation of Title I and the Foreign Intelligence Surveillance Act, 50 U.S.C. §§ 1801-1811 (1988) (the “FISA”). Title I regulates the interception for domestic purposes of “wire, oral, or electronic communication[s],” 18 U.S.C. § 2511(1); its definition of those terms does not include silent video surveillance, see 18 U.S.C. § 2510. The FISA regulates the use for “foreign intelligence” purposes, 50 U.S.C. § 1804(a)(7)(B), of any form of “electronic surveillance,” 50 U.S.C. § 1802, including silent video surveillance, see 50 U.S.C. § 1801(f)(4). The question is what effect, if any, these statutes have on silent video surveillance conducted for purely domestic purposes.
The defendants argue that domestic silent video surveillance is prohibited by Title I, or, alternatively, that it is regulated by Title I; the government claims such surveillance is neither prohibited nor regulated by the statute. The district court found domestic silent video surveillance was prohibited by Title I; the original panel found it was not prohibited, but regulated. We conclude (1) neither Title I nor the FISA prohibits domestic silent video surveillance; (2) Title I does not regulate such surveillance; (3) the Fourth Amendment does regulate such surveillance.
A NEITHER TITLE I NOR THE FISA PROHIBITS DOMESTIC SILENT VIDEO SURVEILLANCE
Title I does not address silent video surveillance. By its terms, the statute governs the interception of “wire, oral, or electronic communications....” 18 U.S.C. *539§ 2511. The statute defines a “wire communication” as “any aural transfer made ... through the use of facilities for the transmission of communications by the aid of wire, cable, or other like connection between the point of origin and the point of reception_” 18 U.S.C. § 2510(1) (emphasis added). An “oral communication” is defined as “any oral communication uttered by a person exhibiting an expectation that such communication is not subject to interception under circumstances justifying such expectation_” 18 U.S.C. § 2510(2) (emphasis added). An “electronic communication” is “any transfer of signs, signals, writing, images, sounds, data, or intelligence of any nature transmitted ... by a wire_” 18 U.S.C. § 2510(12) (emphasis added). Finally, “intercept” means “the aural or other acquisition of the contents of any wire, electronic, or oral communication through the use of any electronic, mechanical, or other device.” 18 U.S.C. § 2510(4) (emphasis added).
By their plain meaning, these definitions do not apply to silent video surveillance. As the Supreme Court stated, discussing 18 U.S.C. §§ 2510-2520 (1968) (amended 1970, 1986, 1988) (“Title III”), the predecessor of Title I,1 the statute “is concerned only with orders ‘authorizing or approving the interception of a wire or oral communication....’” United States v. New York Tel. Co., 434 U.S. 159, 166, 98 S.Ct. 364, 369, 54 L.Ed.2d 376 (1977) (quoting 18 U.S.C. § 2518(1)) (emphasis removed) (omission in New York Tel. Co.). The Court held pen registers2 are not subject to the statute because “[tjhese devices do not hear sound.... [They] do not accomplish the ‘aural acquisition’ of anything[, and they] present the information in a form to be interpreted by sight rather than by hearing.” Id. at 167, 98 S.Ct. at 369-70. This analysis applies equally to silent video surveillance. See United States v. Biasucci, 786 F.2d 504, 508 (2d Cir.) (quoting New York Tel. Co., 434 U.S. at 166, 98 S.Ct. at 369), cert. denied, 479 U.S. 827, 107 S.Ct. 104, 107, 93 L.Ed.2d 54, 56 (1986).
The legislative history of Title I also indicates the statute does not regulate silent video surveillance. “The Senate committee report, after repeating the statutory definition of ‘aural acquisition,’ remarks: ‘Other forms of surveillance are not within the proposed legislation.’ ” United States v. Torres, 751 F.2d 875, 880 (7th Cir.1984) (quoting S.Rep. No. 1097, 90th Cong., 2d Sess. 90 (1968), reprinted in 1968 U.S.C.C.A.N. 2112, 2178), cert. denied, 470 U.S. 1087, 105 S.Ct. 1853, 85 L.Ed.2d 150 (1985).
The 1986 Senate Report on Title I makes clear that Congress did not intend to regulate domestic silent video surveillance. The Report states:
Although this bill does not address questions of the application of title III standards to video surveillance and only deals with the interception of closed circuit television communications to a limited extent, closed circuit television communications do provide another example of the importance of, and the interrelationship between, the definitions contained in this legislation. If a person or entity transmits a closed circuit television picture of a meeting using wires, microwaves or another method of transmission, the transmission itself would be an electronic communication. Interception of the picture at any point without either consent or a court order would be a violation of the statute. By contrast, if law enforcement officials were to install their own cameras and create their own closed circuit television picture of a meeting, the capturing of the video images would not be an intercep*540tion under the statute because there would be no interception of the contents of an electronic communication. Intercepting the audio portion of the meeting would be an interception of an oral communication, and the statute would apply to that portion.
S.Rep. No. 541, 99th Cong., 2d Sess. 16-17, reprinted in 1986 U.S.C.C.A.N. 3555, 3570-71 (emphasis added).
In contrast, it is clear that FISA does regulate silent video surveillance. FISA regulates “electronic surveillance,” 50 U.S.C. § 1802(a), which it defines quite broadly to include:
the installation or use of an electronic, mechanical, or other surveillance device in the United States for monitoring to acquire information, other than from a wire or radio communication, under circumstances in which a person has a reasonable expectation of privacy and a warrant would be required for law enforcement purposes.
50 U.S.C. § 1801(f)(4). This definition clearly includes the use of closed circuit television cameras and other video surveillance equipment. See Torres, 751 F.2d at 881.
However, it is equally clear that the FISA applies only to surveillance designed to gather information relevant to foreign intelligence. See 50 U.S.C. § 1802(a)(1) (“the President ... may authorize electronic surveillance ... under this chapter to acquire foreign intelligence information”); id. § 1802(a)(l)(A)(i)-(ii); id. § 1804(a)(7)(B) (FISA authorizes surveillance only when “the purpose of the surveillance is to obtain foreign intelligence information”). The FISA does not regulate surveillance conducted for purely domestic purposes. See Torres, 751 F.2d at 881.
Together, the FISA and Title I describe an incomplete 2x2 matrix regulating aural and visual electronic surveillance conducted for foreign and domestic purposes.3 The FISA regulates both aural and visual electronic surveillance conducted for foreign intelligence purposes, and Title I regulates aural electronic surveillance conducted for domestic purposes. The fourth and final element of the matrix, visual electronic surveillance conducted for domestic purposes, is not addressed either by Title I or the FISA:
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Ordinarily, of course, when regulatory statutes do not address an activity, the activity is not regulated, and certainly not prohibited, by those statutes. Hence, because domestic silent video surveillance is not addressed by Title I or the FISA, it would appear that it may be conducted without regard to those statutes. However, the defendants argue, and the district court found, that Title I prohibits all electronic surveillance which it does not regulate. The defendants rely on 18 U.S.C. § 2511(2)(f), a provision of the FISA that amended Title III, which provides in pertinent part: “[Procedures in [Title I and the FISA] shall be the exclusive means by which electronic surveillance, as defined in [the FISA], and the interception of domestic wire and oral communications may be conducted.” The defendants argue this provision outlaws any form of electronic surveillance not expressly authorized (and regulated) by Title I or the FISA because those statutes are the “exclusive means” by which electronic surveillance may be conducted.
We reject the defendants’ argument. Like the other circuits that have ruled on this issue, and the original panel of this court, we conclude that neither § 2511(2)(f), nor anything else in the text or legislative history of Title I or the FISA, prohibits silent video surveillance for domestic purposes.
*541All ... section [2511(2)(f) ] means to us ... is that the [FISA] is intended to be exclusive in its domain and Title [I] in its [domain]. The powers that the [FISA] gives the government to keep tabs on agents of foreign countries are not to be used for purely domestic investigations, and conversely the limitations that Title [I] places on wiretapping and bugging are not to be used to hobble the government’s activities against foreign agents. To read the [FISA] as the defendants would have us do would give a statute designed to regularize the government’s broad powers to deal with the special menace posed by agents of foreign powers the side effect of curtailing the government’s powers in domestic law enforcement. This is not what Congress intended in making what the Senate report on the bill that became the [FISA] described as a “technical and conforming” amendment to Title [I]....
The fact is that Congress has never addressed the issue of judicial authorization of television surveillance in [domestic] federal criminal investigations.
Torres, 751 F.2d at 881-82; see Biasucci, 786 F.2d at 508 n. 4 (quoting Torres, 751 F.2d at 881).
B TITLE I DOES NOT REGULATE DOMESTIC SILENT VIDEO SURVEILLANCE
In the alternative to their argument that Title I prohibits domestic silent video surveillance, the defendants claim Title I regulates such surveillance. They argue that interpreting Title I to ignore domestic silent video surveillance “eviscerates” congressional intent because it produces an obvious asymmetry: a regulatory scheme which governs foreign audio surveillance, foreign silent video surveillance, domestic audio surveillance, but not domestic silent video surveillance. The defendants also claim § 2511(2)(f) indicates Congress intended to subject domestic silent video surveillance to the same restrictions as domestic audio surveillance.
Again, we reject the defendants’ arguments. As the dissent to the original panel opinion noted, it is “impossible for silent television surveillance to intercept a ‘wire, oral, or electronic communication.’ ” Koyomejian, 946 F.2d at 1461 n. 1 (Hall, J., dissenting). Unlike the panel majority, we do not believe Congress must have “simply assumed [in 1986] that video surveillance was already regulated by Title III.... ” Id. at 1457. On the record before us, we do not think it “simply ... [unbelievable] that Congress intended the anomalous result of subjecting less intrusive forms of surveillance than video to exacting procedural safeguards while leaving video surveillance itself unregulated.” Id. This statement discounts the strict controls on video surveillance imposed by the Fourth Amendment and Federal Rule of Criminal Procedure 41. See Part II.C, infra.
Further, although Congress’ regulatory scheme is asymmetrical, Congress is not required to think like a lawyer, and we are not empowered to impose on clear statutory language our own notions of symmetry. See Koyomejian, 946 F.2d at 1461 (Hall, J., dissenting); Torres, 751 F.2d at 885-86. Nothing in Title I or the FISA regulates or even discusses domestic silent video surveillance. We cannot rewrite those statutes.
C THE FOURTH AMENDMENT REGULATES DOMESTIC SILENT VIDEO SURVEILLANCE
Although domestic silent video surveillance is not regulated by statute, it is of course subject to the Fourth Amendment. See Torres, 751 F.2d at 882. Although the district court did not pass on the Fourth Amendment issue in this case, we address it nonetheless because it is a purely legal issue, and in the interest of judicial economy. See Badea v. Cox, 931 F.2d 573, 575 n. 2 (9th Cir.1991) (recognizing that this court has the “power” to decide, and that “[t]here may well be valid reasons for” deciding, “ab initio issues that the district court has not had an opportunity to considerf, the parties have not briefed] and that present questions of first impression in our circuit”). We proceed to describe the Constitutional requirements *542for silent video surveillance conducted for domestic purposes.
As a preliminary matter, we conclude that Rule 41(b) of the Federal Rules of Criminal Procedure authorizes a district court to issue warrants for silent video surveillance. See United States v. MesaRincon, 911 F.2d 1433, 1436 (10th Cir.1990) (“Rule 41 is sufficiently flexible to include within its scope electronic intrusions authorized upon a finding of probable cause.’ ” (quoting New York Tel. Co., 434 U.S. at 169, 98 S.Ct. at 371)); Biasucci, 786 F.2d at 509; Torres, 751 F.2d at 877-78.
Second, following the other circuits which have ruled on this issue, we “look to Title [I] for guidance in implementing the fourth amendment in an area that Title [I] does not specifically cover.” Mesa-Rincon, 911 F.2d at 1438. While we do not adopt all of the special, technical requirements of Title I, see, e.g., 18 U.S.C. § 2516, we do adopt the following four requirements, in addition to the ordinary requirement of a finding of probable cause:
(1) the judge issuing the warrant must find 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,” 18 U.S.C. § 2518(3)(c); (2) the warrant must contain “a particular description of the type of [activity] sought to be [videotaped], and a statement of the particular offense to which it relates,” id. § 2518(4)(c); (3) the warrant must not allow the period of [surveillance] to be “longer than is necessary to achieve the objective of the authorization, [ ]or in any event longer than thirty days” (though extensions are possible), id. § 2518(5); and (4) the warrant must require that the [surveillance] “be conducted in such a way as to minimize the [videotaping] of [activity] not otherwise subject to [surveillance] ...,” id.
United States v. Cuevas-Sanchez, 821 F.2d 248, 252 (5th Cir.1987); see Torres, 751 F.2d at 885; Biasucci, 786 F.2d at 510; Mesa-Rincon, 911 F.2d at 1437. We are satisfied that these requirements comport with the demands of the Constitution, and guard against unreasonable video searches and seizures.
Ill CONCLUSION
Neither Title I nor the FISA regulates or prohibits silent video surveillance undertaken for domestic purposes. The Fourth Amendment does govern such surveillance, however, and requires adherence to the non-technical provisions of Title I listed above. The order suppressing the video evidence is vacated, and the case is remanded to the district court to measure the video surveillance against the Constitutional standards announced in this opinion, unless the district court determines that any Fourth Amendment issue has been waived.
VACATED AND REMANDED.
. Title III of the Omnibus Crime Control and Safe Streets Act of 1968, Pub.L. No. 90-351, 82 Stat. 212, was amended and retitled by Title I of the Electronic Communications Privacy Act of 1986, Pub.L. No. 99-508, 100 Stat. 1851. Throughout this opinion, we refer to 18 U.S.C. §§ 2510-2521 as "Title I."
. “A pen register is a mechanical device that records the numbers dialed on a telephone by monitoring the electrical impulses caused when the dial on the telephone is released. It does not overhear oral communications and does not indicate whether calls are actually completed.” New York Tel. Co., 434 U.S. at 161 n. 1, 98 S.Ct. at 366 n. 1.
. This case does not involve, and so the matrix does not address, the interception of silent video images transmitted by wire or other electronic means.