Opinion for the Court filed by Circuit Judge WILKEY.
Opinion concurring filed by Circuit Judge McGOWAN.
[1304]*1304WILKEY, Circuit Judge:
This case addresses a narrow issue of broad international consequence: did Congress expressly or impliedly authorize the Federal Trade Commission (FTC or Commission) to serve its investigatory subpoenas directly upon citizens of other countries by means of registered mail? Although on the surface this question appears to rest solely upon statutory interpretation, our answer to it is primarily guided by our recognition of established and fundamental principles of international law.
Federal courts have long acknowledged that the investigatory 1 and regulatory2 reach of domestic agencies may, and often must, extend across national boundaries. This court has previously recognized that those agencies may under certain circumstances compel production of documents located abroad.3 We cannot, however, simply assume from these precedents that Congress intended to authorize regulatory agencies in general — and the FTC in particular- — to employ any and all methods to serve compulsory process when conducting their investigations. When an American regulatory agency directly serves its compulsory process upon a citizen of a foreign country, the act of service itself constitutes an exercise of American sovereign power within the area of the foreign country’s territorial sovereignty. Though some techniques of service may prove less obnoxious than others to foreign sensibilities, our recognition of those sensibilities must affect our willingness to infer congressional authorization for a particular mode of service from an otherwise silent statute. In the face of the foreign country’s direct protest to the mode of service employed here, and in the absence of clear congressional intent at the time this subpoena was served to authorize that manner of exercise of American sovereign power, we decline to infer the necessary statutory authority for the FTC’s chosen mode of subpoena service.
I. BACKGROUND
Since 1977 the FTC has been engaged in a nonpublic antitrust investigation of the U.S. fiberglass insulation industry to determine whether a number of fiberglass manufacturers and distributors have engaged in acts or practices in violation of section 5 of the FTC Act.4 One of the principal targets of the FTC investigation has been Compagnie de Saint-Gobain-Pont-a-Mousson (SGPM), a French holding company headquartered in Paris, but with a general delegate based in New York City.5 In September 1977 the Commission issued four identi[1305]*1305cal subpoenas duces tecum directing SGPM to produce specified classes of documents relevant to the investigation.6 One copy of the subpoena was served by registered mailing to SGPM’s corporate headquarters in Paris; the second was hand-delivered to the New York office of SGPM’s general delegate in the United States; the third was delivered to the New York City residence of the daughter of SGPM’s general delegate; and the fourth was served upon the Washington, D.C. attorney representing SGPM in a related proceeding.7 When SGPM refused to comply with the subpoenas, the Commission petitioned the district court for an enforcement order pursuant to section 9 of the FTC Act.8 In response to the district court’s order to show cause why the petition should not be granted,9 SGPM asserted that it should be excused from compliance because none of the modes of subpoena service employed were authorized by the FTC Act.10 Finding the subpoena relevant to the Commission’s inquiry and the mode of service to be proper, the district court issued the requested order enforcing the subpoena on 29 September 1978.11
On appeal from the district court’s denial of SGPM’s motion to stay the enforcement order,12 this court remanded the record to the district court.13 Addressing only the issue whether the investigatory subpoena [1306]*1306had been served upon SGPM in a lawful manner, we concluded that the latter three methods of subpoena service employed by the Commission were improper.14 We directed the district court on remand to “examine carefully the validity vel non of [the first method of] service by the registered mailing to [SGPM’s] corporate headquarters in Paris,”15 and in particular, to construe the relevant authorizing statutes to determine the underlying congressional intent.16 At the time we cautioned the district court to pay special attention to whether its construction of the relevant statutes conformed to accepted principles of international law, “since Congress is customarily presumed, unless a plain intention appears to the contrary, to avoid conflict with such principles as well as with the Constitution.” 17
Following argument on remand, the French Embassy sent a note to the State Department, protesting that the FTC’s direct transmittal of its subpoena to SGPM’s Parisian headquarters via registered mail constituted an infringement of French national sovereignty.18 The French government’s protests notwithstanding, the district court concluded that neither the Constitution nor statute “intended to deny the FTC the right to send a subpoena by mail to a foreign corporation suspected ... of unfair trade practices in violation of the Federal Trade Commission Act.”19 Consequently, on 14 February 1980, the district court issued a second order reiterating its original enforcement of the FTC subpoena.20 For reasons articulated below, we vacate both the enforcement order dated 29 September 1978 and the order dated 14 February 1980.
II. ANALYSIS
The sole issue to be resolved on this appeal is the propriety of the technique employed by the FTC to serve its subpoena abroad — namely, registered mailing to a foreign citizen on foreign soil. We will begin by examining whether, at the time service was attempted, the language of the FTC Act expressly authorized service by registered mail of FTC subpoenas abroad and whether the legislative history of the FTC Act and similarly worded statutes revealed any congressional intent to authorize such a mode of service. Next, after clarification of two distinctions blurred by the opinion below, we reject the district court’s conclusions that accepted principles of international law condone the mode of subpoena service employed here. We then suggest that basic canons of statutory construction do not permit authority for such a [1307]*1307mode of subpoena service to be inferred from the FTC’s general jurisdictional mandates to investigate and regulate foreign and interstate commerce.
We conclude that, at the time the subpoena was served, Congress intended to authorize the FTC to employ only those customary and legitimate methods of service of compulsory process commonly employed by American courts and administrative agencies when serving its subpoenas abroad. Because service of compulsory process by registered mail had not customarily proved a legitimate means of summoning a third-party witness to appear, with or without documents, in an agency investigation, we find that the method of service employed by the FTC in this case was unauthorized and hence invalid.
A. Statutory Language and Legislative History
Traditional techniques of statutory construction avail us little in uncovering Congress’ intent regarding proper methods of subpoena service abroad. Opposing counsel acknowledge that, as of the date of the service challenged here, the language of the FTC Act nowhere expressly authorized, nor expressly prohibited, direct service of FTC subpoenas abroad by means of registered mail.21 We shall briefly canvass those statutory provisions potentially applicable at the date of service.
Section 5(f)(c) of the FTC Act, set out in the margin provided that “[cjomplaints, orders, and other processes of the Commission under this section may be served” by registered or certified mail.22 In ruling on SGPM’s motion to quash, however, the Commission correctly read the plain language of section 5(f)(c) not to apply to the service of the investigatory subpoenas challenged here, because such subpoenas, issued under section 6, 9, and 10 of the Act23 simply did not constitute “processes of the Commission under this section [section 5].”24 Nor did section 6(g) of the Act, granting the Commission broad rulemaking authority to shape its investigatory procedures25 authorize or prohibit the manner of service employed here. It is true that this provision had previously been construed to afford the FTC broad discretion in determining which modes of service of process were appropriate.26 In fact, under this statutory section, the FTC promulgated its [1308]*1308Rule of Practice 4.4(a), which specifically authorized service of subpoenas by registered or certified mail.27 Yet rule 4.4(a), as it existed at the time of service, suggested no limits as to where, or upon whom, subpoenas might properly be served.
When the challenged subpoena was served, the only statutory source of instruction as to the permitted geographic range of subpoena service was FTC Act section 9, which empowered the Commission to require by subpoena the attendance of witnesses and the production of documentary evidence relating to a matter under investigation “from any place in the United States, at any designated place of hearing.”28 This seemingly unambiguous language of section 9 (and of statutes incorporating identical locutions)29 had engendered surprising controversy. In FMC v. DeSmedt,30 Judge Friendly reviewed the legislative history of the “from any place in the United States” language of a provision nearly identical to that found in the FTC Act.31 He found that the phrase had first been added to the original ICC Act32 in order to clarify the agency’s power to compel a witness’ appearance by subpoena inside the United States, but outside the boundaries of the judicial district in which the witness resided.33 Despite the note of caution injected by the dissent to DeSmedt,34 this Circuit chose to adopt Judge Friendly’s' rationale virtually without [1309]*1309analysis in CAB v. Deutsche Lufthansa Aktiengesellschaft,35 finding that the language in question “was not intended as a limitation on agency subpoena authority, but rather ... to free the agency of the geographic limitations imposed on subpoenas issued by the district courts.” 36
While these cases clearly suggested that documents might be subpoenaed by regulatory agencies from anywhere inside the United States — and, in some cases, might be obtainable even when located outside the territorial jurisdiction of the United States37 — they by no means suggested that Congress intended the FTC subpoena power to have no place or manner limits whatever. Neither opinion cast light on the modes of subpoena service expressly endorsed by the legislative branch — in neither DeSmedt nor Lufthansa was the propriety of the technique of subpoena service at issue. Furthermore, neither case expressly considered the particular situation before us — subpoena service upon a foreign citizen residing on foreign soil.38 Thus, neither the terms of the relevant statute, nor the cases interpreting those terms, conclusively settle the novel issue before us.
Nor does the legislative history of the FTC Act or similar statutes afford us any guidance. Both parties agreed,39 and the court below acknowledged,40 that at the time of service the history of the Act was “wholly silent” regarding which modes of foreign service of investigatory subpoenas were or were not proper.
[1310]*1310Confronted with both a silent statute and an uninstructive legislative history, the district court sought guidance in the breadth of authority granted by the Constitution to Congress to regulate commerce with foreign nations — a power “as great if not greater, than its power to regulate interstate commerce.”41 When Congress created the FTC as the agency charged with investigation and regulation of unfair trade practices, the district court concluded, it must have intended that agency to wield the “broadest power to make commerce, foreign and domestic, fair.”42 From the FTC’s discretionary authority to investigate and regulate foreign commerce, the district court thus inferred the Commission’s power to serve its process abroad:
It seems beyond reasonable dispute that the FTC could not faithfully execute its congressional mandate to investigate and enforce laws regulating foreign and domestic commerce if its process could not reach companies incorporated and headquartered abroad which nevertheless have substantial and continuing impacts on the foreign and domestic commerce of the United States.43
Since past judicial interpretations of statutory language identical to that in FTC Act section 9 had studiously avoided “reading into the statute artificial limits on the investigatory power of the agencies,”44 the district court chose to read that section as presumptively authorizing the FTC to deliver its subpoenas over a limitless geographic area.45
By implication, the district court also created a presumption in favor of any means of subpoena service which the FTC might decide to employ.46 In creating this presumption, the court explicitly rejected the notion that any “clear statement” of congressional intent was required to authorize any particular method of foreign service. Not only had Congress previously authorized direct service of process abroad without such a “clear statement,”47 the court suggested, but there are no “generally applicable principles of international law regarding [permissible or impermissible] methods of service to which Congress might be expected to defer.”48
We find the district court’s opinion unconvincing because of its failure to draw two distinctions of critical importance in international law: the first, based on the type of document being served; the second, based on the type of jurisdiction being invoked. By failing to draw these crucial distinctions, the district court failed to give adequate weight to fundamental principles of international law which disfavor methods of extraterritorial subpoena service circumventing official channels of judicial assistance49 oppose judicial enforcement of investigatory subpoenas abroad,50 and prohibit the particular manner of subpoena service employed here.51
B. The Legitimacy of the FTC’s Method of Service Under International Law
1. The Nature of the Document Served
As one of several targets of an FTC investigation which remains in a preliminary phase, SGPM has neither the status of an accused in a criminal action nor the status of a defendant in a civil action. Al[1311]*1311though as a result of the agency investigation, SGPM may eventually be named a defendant in a civil action, presently it is merely a third-party witness on notice of its potential status as a party defendant. The FTC’s subpoena duces tecum and accompanying letter ought not, therefore, be viewed merely as a summons giving notice of a complaint initiating a lawsuit against SGPM. Rather, the FTC’s issuance of a subpoena and the district court’s enforcement thereof, represent a classic exercise of compulsory process, intended to secure the personal appearance of and production of documents by an otherwise unwilling witness through threat of judicial sanctions for noncompliance.52
The distinction between service of notice and service of compulsory process is a crucial one under principles of both domestic and international law. When an agency serves a party with notice of the pendency of an action, it thereby supplies the recipient with information upon which he may base a decision to act or not. When an agency serves compulsory process upon a third-party witness, regardless of the technique of service employed, it effectively compels that witness to do something and threatens him with sanctions should he choose not to comply. Thus, when the FTC issues and serves a formal complaint upon a respondent, charging him in an adjudicative proceeding with violation of one or more of the statutes it administers, the purpose of service is primarily notice, rather than compulsion53 Once the respondent is served with a copy of the complaint and the proposed order, he then has the options of meeting with the Commission’s counsel to negotiate a consent order or of proceeding to litigation, the result of which may always be appealed before any cease-and-desist order may issue. Not until the cease- and-desist order becomes final, through affirmance by a court of appeals or the Supreme Court (if taken to that Court by certiorari), will the coercive power of the courts be directly brought to bear upon the respondent.54
When a witness is served with compulsory process in the form of an investigatory subpoena, however, the consequences of noncompliance are strikingly different.55 Should the witness fail to produce material responsive to the subpoena, the full enforcement power of the federal courts may immediately be brought to bear upon him. Disobedience is itself both a statutory crime and an occasion for imposition of a money penalty.56 The Commission.may seek a judicial order directing compliance or a finding that the respondent is in contempt of court.57 Summary proceedings may be be[1312]*1312gun under Fed.R.Civ.P. 81(a)(3),58 with a finding of contempt the ultimate penalty.59 In the event of continued noncomplianee, a district court could presumably enforce its order by seizing the noncomplying respondent’s assets wherever they might be found and lawfully attached,60 by holding the officers and agents of the corporation in contempt, or by otherwise exercising its discretion to punish a potential witness’ recalcitrance. Unlike service of a summons and complaint upon a named defendant, delivery of the FTC’s investigatory subpoena upon a witness carries with it the full array of American judicial power.
The distinction between notice and compulsory process, and the implications of that distinction for permissible modes of service, is well illustrated in the context of civil litigation. Federal Rule of Civil Procedure 4, which governs service of process, is primarily concerned with effectuating notice.61 To that end, the rule provides for a wide range of alternative methods of service, including registered mail, each designed to ensure the receipt of actual notice of the pendency of the action by the defendant.62 By contrast, Federal Rule 45(c), governing subpoena service, does not permit any form of mail service, nor does it [1313]*1313allow service of the subpoena merely by delivery to a witness’ dwellingplace.63 Thus, under the Federal Rules, compulsory process may be served upon an unwilling witness only in person. Even within the United States, and even upon a United States citizen, service by registered U.S. mail is never a valid means of delivering compulsory process, although it may be a valid means of serving a summons and a complaint.64
When the individual being served is not an American on U.S. soil but a foreign subject on foreign soil, the distinction between the service of notice and the service of compulsory process takes on added significance. When process in the form of summons and complaint is served overseas, the informational nature of that process renders the act of service relatively benign.65 When compulsory process is served, however,, the act of service itself constitutes an exercise of one nation’s sovereignty within the territory of another sovereign.66 Such an exercise constitutes a violation of international law.67 Given its informational nature, service of process from the United States into a foreign country by registered mail may thus be viewed as the least intrusive means of service — i. e., the device which minimizes the imposition upon the local authorities caused by official U.S. government action within the boundaries of the local state.68 Given the compulsory nature of a subpoena, however, subpoena service by direct mail upon a foreign citizen on foreign soil, without warning to the officials of the local state and without initial request for or prior resort to established channels of international judicial assistance,69 is perhaps maximally intrusive.70 [1314]*1314Not only does it represent a deliberate bypassing of the official authorities of the local state,71 it allows the full range of judicial sanctions for noncompliance with an agency subpoena to be triggered merely by a foreign citizen’s unwillingness to comply with directives contained in an ordinary registered letter.
The district court failed to recognize either of these consequences in enforcing the Commission’s subpoena. The district court’s opinion cited a number of state and federal statutes governing judicial service of process abroad to justify the assertion that no clear congressional authorization is necessary before an agency may employ a particular form of subpoena service abroad.72 Although it is true that Federal Rule of Civil Procedure 4(i)(1)(D) specifically permits service of process abroad “by any form of mail, requiring a signed receipt,”73 that subprovision, when read together with the other four modes of foreign service of process provided in rule 4(i), underlines rather than obviates the need for judicial sensitivity to foreign territorial sovereignty when scrutinizing particular methods of overseas service.74 Furthermore, the refer[1315]*1315enees made in rule 4(i) to alternative official channels for foreign service75 indicate that the district court erred in construing congressional silence as authorizing regular and unrestrained circumvention of a foreign nation’s judicial authorities76 In view of the significant sanctions conditionally imposed by the agency’s subpoena and the foreign sensibilities aroused by the mode of delivery used here,77 the district court’s finding that Congress “intended” the FTC to deliver its compulsory processes solely with the aid of foreign postal authorities seems mistaken.
2. The Nature of the Jurisdiction Invoked by the FTC’s Service
The exercise of jurisdiction by any governmental body in the United States is subject to limitations reflecting principles of international and constitutional law, as well as the strictures of the particular statute governing that body’s conduct. When more than one nation is involved, jurisdictional issues are often elusive. Some jurisdiction which American governmental bodies might exercise consistently with the U.S. Constitution and laws could violate international law, while some exercises of jurisdiction to which international law does not object may violate the Constitution or laws of the United States. The jurisdictional questions posed by this case are peculiarly complex because the jurisdiction of three institutions is at issue: the jurisdiction of the nations involved, under international law, to require production of documents by a French citizen on French soil; the jurisdiction of the federal courts to enforce the agency’s subpoena; and the jurisdiction of the agency to effect service of its subpoena by registered mail.
a. The International Jurisdiction of States
The Restatement (Second) of the Foreign Relations Law of the United States distinguishes two types of jurisdiction of a state: jurisdiction to prescribe and jurisdiction to enforce.78 Jurisdiction to prescribe signifies a state’s authority to enact laws governing the conduct, relations, status or interests of persons or things, whether by legislation, executive act or order, or administrative rule or regulation.79 Jurisdiction to enforce, by contrast, describes a state’s authority to compel compliance or impose sanctions for noncompliance with its administrative or judicial orders.80 International [1316]*1316law imposes different limitations upon a state’s exercise of its jurisdiction, depending upon whether the jurisdiction exercised is prescriptive or enforcement jurisdiction.81
Traditionally, a state has plenary power to prescribe rules within its own territorial boundaries.82 Conversely, under traditional principles of absolute territoriality, “[the laws of a nation] can have no force to control the sovereignty or rights of any other nation within its own jurisdiction.”83 Over time these rigid principles have yielded to certain exceptions. Thus, the current Restatement recognizes that a state has prescriptive jurisdiction not only over conduct, things, status or interests within its territory,84 but also over conduct outside its territory which has or is intended to have substantial effects within its territory 85 as well as conduct of its nationals even when they are outside its borders.86
When an American court orders enforcement of a subpoena requiring the production of documents and threatens penalties for noncompliance with that subpoena, it invokes the enforcement jurisdiction, rather than the prescriptive jurisdiction, of the United States.87 The two types of jurisdiction are not geographically coextensive —“[a] state having jurisdiction to prescribe a rule of law does not necessarily have jurisdiction to enforce it in all cases,”88 for unlike a state’s prescriptive jurisdiction, which is not strictly limited by territorial boundaries, enforcement jurisdiction by and large continues to be strictly territorial.89 The Restatement illustrates this disjunction with the following hypothetical:
X is a national of state A residing in state B. A has jurisdiction to prescribe a rule subjecting X to punishment if he fails to return to A for military service. X does not return. A has no jurisdiction to enforce its rule by action against X in the territory of B.90
If a state should enforce a rule which it does not have jurisdiction to enforce, it violates international law, thus giving rise to a claim by the state adversely affected which may then be adjudicated in [1317]*1317an appropriate international forum.91 This would be true even if the state had jurisdiction to prescribe the rule in the first place.
Again, the Restatement provides a clear illustration of how such a claim might arise:
X, a national of state A, kills a man in the territory of state B, and escapes to A. Public officers of B seize X in the territory of A and bring him back to B for trial. B has jurisdiction to prescribe criminal rules dealing with the conduct of X but no jurisdiction to take enforcement action in the territory of A. A has a claim against B under the rule (of international law) stated in this Section.92
Similarly, the district court’s enforcement order here violates the above principles of international law — not because the United States lacks jurisdiction to prescribe rules relating to the antitrust matters under investigation, but because the court’s order represents an attempt by the U. S. to exercise its enforcement jurisdiction within foreign territory before its prescriptive jurisdiction over the investigated conduct has been proved to exist.
More than a decade ago, one commentator analyzed a situation identical to the one before us, under principles of international law, in the form of a hypothetical problem:
[Suppose a] court orders aliens to produce documents both located abroad and related to their business activities abroad. The only valid basis of legislative [prescriptive] jurisdiction which could be invoked is the ... [so-called] “effects doctrine.” It must be proved that the commercial activities engaged in abroad had a harmful effect on the economy in the forum country. When a court, however, orders the production of documents, it is still in its investigatory stage. The documents are needed to prove the effects. Hence, the order is made before there is a finding as to whether or not effects exist. This means that the order is issued before legislative jurisdiction is proved to exist. Consequently, this would be an exercise of enforcement jurisdiction without legislative jurisdiction and, thus, contrary to international law.93
Two separate conferences of the International Law Association have also studied this problem and reached the same conclusion — that the district court’s proposed enforcement of the administrative subpoena, by compelling the conduct in France of French nationals, would violate international law. The Fifty-First Conference, held in Tokoyo, initially concluded that:
It is difficult to find any authority under international law for the issuance of orders compelling the production of documents from abroad. The documents are admittedly located in the territory of another State. To assume jurisdiction over documents located abroad in advance of a finding of effect upon commerce raises the greatest doubts among [1318]*1318non-Americans as to the validity of such orders.94
The Fifty-Second Conference of the International Law Association, held in Helsinki, went on to draw a clear distinction between the type of production ordered in DeSmedt95 and the type ordered here:
[T]he basic principle is that the jurisdiction to order production of documents must be commensurate with the limits of the legislative [prescriptive] jurisdiction to regulate the matters to which the documents relate. Thus, the true legal position will be as follows:
(1) Where a State requires a local branch [of a foreign company] to produce documents relating to its own affairs, the demand cannot be resisted merely because the documents are not within the jurisdiction or that they belong to a nonresident alien. A case may arise when the discovery is prohibited by his lex situs [the law of the residence of the alien and the documents]. In such case, each State is acting within its jurisdiction, the one in requiring production and the other in forbidding it, and a conflict arises.
(4) Where, however, a State proceeds against a local branch to enforce the production of documents situate abroad and moreover relating to the affairs or to activities outside the jurisdiction of the head-office of the non-resident alien, the requirement is only lawful if the enforcing State has, in fact, substantive jurisdiction to enquire into those affairs and activities. A State abuses its powers if it uses the process of its courts to reach further than its legislative jurisdiction properly extends.96
By this analysis, the district court’s enforcement of the FTC’s subpoenas so served would clearly extend American enforcement jurisdiction beyond the limits of its prescriptive jurisdiction. As such, the district court’s enforcement order violated a fundamental principle of international law.
b. Types of Agency and Federal Court Jurisdiction Distinguished
When a state’s jurisdiction to adjudicate,97 as opposed to its enforcement or prescriptive jurisdiction, is at issue, questions of service of process, subject matter jurisdiction, and personal jurisdiction are invariably intertwined and hence, frequently confused. Before a federal court may adjudicate a controversy, it must possess jurisdiction over both the subject matter of the action and over the persons whose rights are to be affected by its determination.98 Both types of jurisdiction are constitutionally limited. The subject matter jurisdiction of the federal courts depends totally upon congressional implementation of a constitutional grant of subject matter jurisdiction.99 Furthermore, federal courts are subject to limits of personal jurisdiction — a court may not exercise its adjudicatory au[1319]*1319thority 'over an individual unless it has power to reach him, as circumscribed by the due process clause of the Constitution.100 Under modern doctrine,101 due process is not satisfied unless the defendant has sufficient “minimum contacts” with the forum such that the maintenance of a lawsuit against him in that forum does not offend “traditional notions of fair play and substantial justice.”102 Procedural due process further, requires that a court not exercise its adjudicatory authority over a person, even when it has the power to do so, unless that person has been given adequate notice and opportunity to be heard103 Thus a court may lack personal jurisdiction over an individual either because it is powerless to affect his rights or because it has failed to give him proper notice that his rights are at issue.
If properly accomplished, service of process confers personal jurisdiction upon a court to adjudicate the rights of a party.104 When as here, the issue is the propriety of a particular technique of serving a particular type of process, however, neither subject matter jurisdiction nor personal jurisdiction — in either the “power” or the “notice” sense — is directly at issue.105 The basic inquiry here is thus whether the district court’s enforcement order should be vacated because the manner used by the agency to serve its subpoena was unauthorized by, or in in some other way obnoxious to, domestic or international law.
The district court, however, apparently viewed the central issue in the case as whether or not the power of the FTC to serve process abroad could validly be inferred from its broad investigatory and regulatory jurisdiction.106 The court read Blackmer v. United States107 as “unequivocally concluding] that the lawful exercise of jurisdiction confers the authority to effect service.”108 It then postulated that since the Blackmer Court had upheld Congress’ power expressly to authorize issuance of subpoenas abroad, it must have also approved Congress’ power to secure service of those subpoenas. By delegating its subpoena power to the FTC, the district court concluded, Congress by implication must have delegated to the agency authority to effect subpoena service in any permissible manner.109
Such an analysis fundamentally misreads the Supreme Court’s jurisdictional findings in Blackmer, as a review of the history of that case will demonstrate. Upon discovery of the Teapot Dome scandal in 1923, a number of the prominent Americans involved, among them Harry Blackmer, fled to France. To compel their testimony in the subsequent criminal proceedings, Congress passed the Walsh Act110 authorizing the [1320]*1320federal district courts to compel the attendance of American witnesses abroad in connection with domestic criminal proceedings. The statute expressly authorized service of judicial subpoenas outside the United States and specified the means of service to be employed.111 Pursuant to the Act, the Supreme Court of the District of Columbia issued a subpoena which was served upon Blackmer in the statutorily authorized fashion, requiring Blackmer to appear as a witness at a criminal trial. When Blackmer failed to respond, he was found in contempt of court. The U. S. Supreme Court affirmed the contempt conviction and upheld the statute against a due process attack solely on the grounds that Blackmer “was, and continued to be, a citizen of the United States.”112
The Blackmer Court found the statute consistent with both the Constitution and international law for two reasons. With respect to the exercise of the United States’ prescriptive authority over Blackmer, the Court found “there is no question of international law, but solely of the purport of the municipal law which establishes the duties of the citizen in relation to his own government,” namely, the duty “which the citizen owes to his government ... to support the administration of justice by attending its courts and giving his testimony whenever he is properly summoned.”113 With respect to the exercise of the United States’ adjudicative authority over Blackmer, the Court held that the trial court’s authority to give Blackmer constitutionally required notice was a necessary adjunct of its judicial power over him, which in turn was independently based upon the contact provided by his American citizenship.114
Upon examination, this case bears little resemblance to Blackmer. In Blackmer, the primary question was one of personal jurisdiction: whether Blackmer’s American citizenship provided a sufficient basis for the court’s assertion of its adjudicatory power over him.115 The witness did not challenge the subject matter jurisdiction of the court; Congress had by statute explicitly delegated to the court the authority to issue its subpoenas abroad as part of its general jurisdiction to adjudicate. Nor did Blackmer question whether Congress had authorized the particular technique of service employed. In the Walsh Act, Congress had clearly stated its intent to equip courts with a means by which to serve American witnesses abroad to procure their attendance in criminal proceedings.116 Thus [1321]*1321the only question of international law discussed in Blackmer was whether Congress, by enacting the Walsh Act, had exceeded its prescriptive jurisdiction.117
Here, by contrast, the primary questions are those of subject matter jurisdiction and technique of service. At the time of service, Congress had explicitly conferred subject matter jurisdiction on the agency to investigate conditions which may affect America’s foreign trade, but it had not explicitly delegated to the agency any authority to serve its subpoenas on foreign citizens abroad.118 In Blackmer, the congressional intent regarding the proper method of service was unmistakable; here, it is precisely the congressional intent with respect to technique of service which is in dispute.
In direct contradistinction to Blackmer, in this case the personal jurisdiction of both the district court and the agency over the respondent is not at issue: the court has secured personal jurisdiction over the respondent by proper service of process and, misguidedly or not, the respondent has conceded that the documents being sought are subject to the personal jurisdiction of the agency.119 The relevant issues under international law, therefore, are whether the FTC has properly served its subpoena and whether the court exceeded its enforcement jurisdiction by enforcing that subpoena.
[1322]*1322The district court chose to answer the question of the propriety of the FTC’s method of service by reference to the agency’s subject matter jurisdiction.120 Thus, the district court derived the agency’s specific authority to serve its subpoena abroad in the manner chosen not from any federal statute, but solely by implication from the agency’s general investigatory and regulatory jurisdiction. In view of the prevailing principles of international law opposing that mode of service,121 we will examine whether such an implication was warranted.
C. The Appropriate Interpretation of Congressional Intent Regarding FTC Subpoena Service
In the Federal Trade Commission Act, Congress empowered the FTC “to prevent persons, partnerships, or corporations . . . from using unfair methods of competition in commerce and unfair or deceptive acts or practices in commerce.”122 The Act went on to define commerce to include both interstate and international commerce;123 furthermore, the Commission was statutorily empowered to gather and compile information and
[t]o investigate, from time to time trade conditions in and with foreign countries where associations, combinations, or practices of manufacturers, merchants or traders, or other conditions, may affect the foreign trade of the United States 124
Courts have customarily granted broad deference to an agency’s own initial determination of the scope of its investigatory authority.125 Indeed, there can be little doubt that when the FTC has sought to carry out its statutory mandate within the borders of the United States, the federal courts have chosen to construe its subpoena powers very broadly.126
It is essential to bear in mind, however, the distinction between the narrow issue addressed in this case — namely, the validity of the method of subpoena service actually employed by the FTC — and the larger question of the FTC’s authority to investigate both domestic and foreign corporations whose actions have harmful effect on U.S. commerce. Clearly, the FTC has subject matter jurisdiction to investigate and regulate any of respondent’s activities which affect United States commerce. Yet the fact of this broad subject matter jurisdiction in no way warrants the presumption that the FTC can use any technique to serve a subpoena compelling a foreign company residing abroad to produce live witnesses and documents.127
Liberal judicial interpretations of agency power are not justified when agency action threatens to have extraterritorial, rather than merely national, impact. In Foley Bros. v. Filardo, the Supreme Court stated:
The canon of construction which teaches that legislation of Congress, unless a contrary intent appears, is meant to apply only within the territorial jurisdiction of the United States ... is a valid approach whereby unexpressed congressional intent may be ascertained.128
[1323]*1323Furthermore, as we noted in our original opinion ordering remand,129 courts are bound wherever possible to construe strictly federal statutes conferring subject matter jurisdiction on domestic agencies to avoid possible conflicts with contrary principles of international law.130
The reverse side of this general canon of statutory construction, of course, is that courts of the United States are nevertheless obligated to give effect to an unambiguous exercise by Congress of its jurisdiction to prescribe even if such an exercise would exceed the limitations imposed by international law.131 Given the plain intrusion upon French national sovereignty resulting from the FTC’s direct service of its compulsory process abroad132 and the violation of international law which would result if the district court were to enforce the subpoena here,133 the only issue is whether the provisions which governed subpoena service within the FTC Act at the time of the challenged service could have been sensibly construed so as to avoid conflict with international law.
In view of the international interests at stake, we suggest that, at the time of service, the best reading of congressional intent with regard to permissible modes of subpoena service was one authorizing the FTC to use all customary and legitimate methods of service of compulsory process commonly employed by American courts and administrative tribunals.134 Such a reading would have imposed the requirement of personal service found in Federal Rule of Civil Procedure 45(c), governing permissible methods of subpoena service by a federal court,135 upon FTC subpoenas as well. It would have further required that wherever possible, an agency attempting subpoena service on foreign citizens residing on foreign soil should make initial resort through established diplomatic channels or procedures authorized by international convention.136
[1324]*1324To interpret the congressional intent underlying the FTC Act as authorizing methods of agency subpoena service abroad less rigorous than the means-used to serve judicial subpoenas domestically have run counter to common intuition. To illustrate, if a civil litigant sought to subpoena a California corporation to appear and produce documents in a Washington, D.C. federal court proceeding, that litigant would, under the Federal Rules, be required to have his subpoena delivered in person by a United States marshal or another responsible adult.137 Were the litigant simply to send the subpoena by registered letter to the corporation’s principal offices in California, and the corporation were to resist compliance, the Washington, D.C. district court would refuse to enforce the subpoena. Even if the district court had personal jurisdiction over the foreign corporation, based upon the existence of minimum contacts between the corporation and the District of Columbia, and even if the witness had received actual notice of the proceeding, the improper technique of service employed would cause the court to refrain from citing the recalcitrant witness for contempt. In accordance with rule 45, the district judge would direct the litigant to obtain personal service upon the witness in California, or alternatively, to serve the corporation’s agent in Washington, D.C.138 We cannot imagine that when Congress enacted the FTC Act in 1914 it could have intended an administrative agency such as the FTC to procure witnesses and documents from abroad by means which no civil litigant had ever been able to employ within the borders of the United States. Nor can we imagine that Congress originally intended that the federal courts exercise their enforcement powers to aid administrative agency investigations initiated by registered mail, without making provision for the inevitable infringements upon foreign sovereignty which would result from such exercises.139
Should the FTC be able to obtain personal service upon the president, an officer, or a director of SGPM within the territorial boundaries of the United States, it could validly obtain a judicial enforcement order for that subpoena. Furthermore, we take judicial notice of a recent congressional amendment to the FTC Act, enacted after the subpoena challenged here issued, which apparently gives the FTC express authority to serve its civil investigative demands upon “any person who is not found within the territorial jurisdiction of any court of the [1325]*1325United States, in such manner as the Federal Rules of Civil Procedure prescribe for service in a foreign nation.”140 Because we are concerned here solely with interpreting the congressional intent underlying the FTC Act as it existed at the time of the challenged service, we need not express any opinion at this time as to whether the FTC could now lawfully serve its compulsory process abroad by registered mail as a civil investigative demand governed by the terms of the amended provision. We note only that, even if expressly authorized by statute, such a mode of service might still be subject to a due process attack if the witness so served both refused to concede the personal jurisdiction of the agency and lacked the requisite minimum contacts with the United States.141 Furthermore, under the principles of international law discussed above, such a manner of statutory service might still violate international law.142
Even if the agency could accomplish proper service by the means we have described, the issue of whether it could actually obtain the documents in question is far from settled. Proper service of the FTC’s subpoena would merely create an obligation upon SGPM under American law to furnish the documents. The zeal with which American litigators have recently engaged in antitrust discovery abroad and the willingness of American courts to order production of foreign documents have not only triggered international controversy143 and academic debate;144 they have prompted passage of a fresh wave of foreign non-dis[1326]*1326closure laws as well.145 Indeed, since the instant litigation began, the French government has enacted a statute which would not only subject SGPM to criminal and monetary penalties for producing the documents sought here,146 but would also potentially subject the FTC to criminal penalties under French law merely for “ask[ing] for ... information of an economic, commercial, industrial, financial or technical nature that may constitute proof with a view, to legal or administrative proceedings in another country.” 147 Though we express no view here as to whether SGPM’s noncompliance with a properly served subpoena would be excused in light of the French statute148 the potentially dire consequences of properly obtained service for both the agency and [1327]*1327the respondent influence our decision strictly to construe the congressional intent underlying the statutory provisions relevant here. Without granting undue deference to the mandate of foreign nondisclosure laws,149 we note simply that where two constructions of a statute are possible, the one less likely to conflict directly with regulations of other nations should be chosen.150
III. CONCLUSION
Finding the Commission’s investigatory subpoena to be improperly served under the Federal Trade Commission Act, as we have construed it in conformity with general principles of international law, we order that the district court’s enforcement orders of 29 September 1978 and 14 February 1980 be vacated and that the case be dismissed by the district court. The order of dismissal should also prescribe that all documents and copies submitted by SGPM to the FTC responsive to the improperly served subpoena be returned to SGPM within sixty days after entry of judgment, and that all notes, extracts, or other records derived from such documents be destroyed.
So Ordered.