Opinion for the court filed by J. SKELLY WRIGHT, Circuit Judge.
Dissenting opinion filed by ROBB, Circuit Judge.
[737]*737J. SKELLY WRIGHT, Circuit Judge:
The present case represents yet another phase in the ongoing controversy between petitioner National Organization for the Reform of Marijuana Laws (NORML) and respondent Drug Enforcement Administration (DEA), an agency within the Department of Justice.1 NORML has been seeking to effect a change in the controls applicable to marihuana under the Controlled Substances Act of 1970, 21 U.S.C. § 801 et seq. (1970) (CSA or Act). Respondent DEA has resisted those efforts by citing United States treaty obligations under the Single Convention on Narcotic Drugs, opened for signature March 30,1961,18 U.S.T. 1407, 30 T.I.A.S. No. 6298, 520 U.N.T.S. 151 (Single Convention).2 A brief overview of the pertinent portions of those laws is necessary to a meaningful discussion of the background of this litigation.
I. THE CONTROLLED SUBSTANCES ACT
In 1970 Congress enacted the Controlled Substances- Act, a comprehensive statute designed to rationalize federal control of dangerous drugs.3 The Act contains five categories of controlled substances, designated as Schedules I through V4 and defined in terms of dangers and benefits of the drugs.5 21 U.S.C. § 812(b)(l)-(5). The control mechanisms imposed on manufacture, acquisition, and distribution of substances listed under the Act vary according to the schedule in which the drug is contained.6 In drafting the CSA Congress placed marihuana in Schedule I,7 the classification that provides for the most severe controls and penalties.
Recognizing that the results of continuing research might cast doubt on the wisdom of initial classification assignments,8 [738]*738Congress created a procedure by which changes in scheduling could be effected. Pursuant to Section 201(a) of the,Act, 21 U.S.C. § 811(a), the Attorney General “may, by rule,” add a substance to a schedule, transfer it between schedules, or decontrol it by removal from the schedules.9 A reclassification rule10 promulgated under this section must be made on the record after opportunity for hearing, in accordance with the rulemaking procedures prescribed by the Administrative Procedure Act, 5 U.S.C. ch. 5, subch. II (1970). Section 201(a) further provides that rescheduling proceedings may be initiated by the Attorney General on his own motion, at the request of the Secretary of Health, Education and Welfare, or, as in the present case, on petition of any interested party.
At the heart of the present controversy is the statutory requirement that the Attorney General share his decisionmaking function under the Act with the Secretary of HEW. Specifically, Section 201(b), 21 U.S.C. § 811(b), provides that prior to commencement of reclassification rulemaking proceedings the Attorney General must “request from the Secretary a scientific and medical evaluation, and his recommendations, as to whether such drug or other substance should be so controlled or removed as a controlled substance.” The evaluation prepared by the Secretary must address the scientific and medical factors enumerated in Section 201(c), 21 U.S.C. § 811(c); these factors relate to the effects of the drug and its abuse potential. Pursuant to Section 201(b), the Secretary’s recommendations “shall be binding on the Attorney General as to such scientific and medical matters, and if the Secretary recommends that a drug or other substance not be controlled, the Attorney General shall not control the drug or other substance.”11
Section 201(d) of the Act, 21 U.S.C. § 811(d), contains a limited exception to the referral procedures detailed in Section 201(b)-(c). Subsection (d) provides:
If control is required by United States obligations under international treaties, conventions, or protocols in effect on the effective date of this part, the Attorney General shall issue an order controlling such drug under the schedule he deems most appropriate to carry out such obligations, without regard to the findings required by subsection (a) of this section[12] or section 812(b) of this title[13] and without regard to the procedures prescribed by subsections (a) and (b) of this section.
The issue that has produced the widest gulf between the parties is the effect of subsection (d) on the decisionmaking procedures triggered by NORML’s petition to decontrol or reschedule marihuana. Respondent argues that where, as here, United States treaty obligations require any measure of control over a substance, Section 201(d) relieves the Attorney General of his duty to refer the petition to the Secretary of HEW. Petitioner takes the position that subsection (d) does not obviate the statutory referral requirement, but merely authorizes the At[739]*739torney General to override the Secretary’s recommendations to the extent those recommendations conflict with United States treaty commitments.
II. THE SINGLE CONVENTION ON NARCOTIC DRUGS
In 1948, in order to simplify existing treaties and international administrative machinery, members of the United Nations undertook codification of a single convention on international narcotics control.14 In 1961, after three preliminary drafts, the Single Convention on Narcotic Drugs was opened for signature. The United States ratified the Single Convention in 1967-three years prior to enactment of the Controlled Substances Act.
Like the CSA, the Single Convention establishes several classifications or “schedules” of substances, to which varying regimes of control attach.15 Schedule I of the Single Convention contains substances considered to carry a relatively high abuse liability; included in this category are heroin, methadone, opium, coca leaf, and cocaine.16 Schedules II and III contain those substances regarded as less susceptible to abuse.17 Finally, Schedule IV of the Single Convention — unlike CSA Schedule IV — embraces certain Schedule I substances, such as heroin, the abuse liability of which is not offset by substantial therapeutic advantages.18
In contrast to the CSA,19 the Single Convention prescribes different controls for various parts of the cannabis plant, as defined in Article 1, H 1:
(b) “Cannabis” means the flowering or fruiting tops of the cannabis plant (excluding the seeds and.leaves when not accompanied by the tops) from which the resin has not been extracted, by whatever name they may be designated.
(c) “Cannabis plant” means any plant of the genus cannabis.
(d) “Cannabis resin” means the separated resin, whether crude or purified, obtained from the cannabis plant.
“Cannabis” and “cannabis resin” are listed in Schedules I and IV of the Single Convention and thus are subject to the controls applicable to each of those classifications. As Schedule I drugs20 cannabis and cannabis resin carry the following restrictions:21 Parties to the Single Convention are required to limit production, distribution, and possession of the drugs to authorized medical and scientific purposes.22 Parties must [740]*740license and control all persons engaged in manufacture23 or distribution24 of the drugs and must prepare detailed estimates of national drug requirements25 and specified statistical returns.26 Parties may not permit possession of the drugs “except under legal authority.”27 Finally, the treaty directs the parties to impose certain penal sanctions.28
Cannabis and cannabis resin and other substances listed in Schedule IV invoke additional restrictions, set forth in Art. 2,15:
(a) A Party shall adopt any special measures of control which in its opinion are necessary having regard to the particularly dangerous properties of a drug so included; and
(b) A Party shall, if in its opinion the prevailing conditions in its country render it the most appropriate means of protecting the public health and welfare, prohibit the production, manufacture, export and import of, trade in, possession or use of any such drug except for amounts which may be necessary for medical and scientific research only, including clinical trials therewith to be conducted under or subject to the direct supervision and control of the Party.[29]
As a result of the treaty’s definition of “cannabis,” the controls applicable to cannabis and cannabis resin apply to the leaves and seeds of the cannabis plant when they accompany the “flowering or fruiting tops” of the plant. However, when separated from the tops the leaves and seeds do not fall within the definition of “cannabis” or “cannabis resin” and are not subject to the controls applicable to Schedule I or IV substances.30 Art. 28, If 3 is the only provision that applies po separated leaves:
The Parties shall adopt such measures as may be necessary to prevent the misuse of, and illicit traffic in, the leaves of the cannabis plant.
The only provision arguably relevant to cannabis seeds is Art. 2,18, which provides:
The Parties shall use their best endeavors to apply to substances which do not fall under this Convention, but which may be used in the illicit manufacture of drugs, such measures of supervision as may be practicable.[31]
[741]*741III. HISTORY OF THE LITIGATION
A. The first court case.
On May 18, 1972 petitioner NORML and two other interested parties32 petitioned the Director of the Bureau of Narcotics and Dangerous Drugs (BNDD) to initiate proceedings to remove marihuana from control under the CSA or, alternatively, to transfer the substance from Schedule I to Schedule V. On September 1, 1972 the Director, as delegee of the Attorney General,33 refused to accept the petition for filing. 37 Fed. Reg. 18097 (1972). He stated that decontrol or reclassification of marihuana would violate United States treaty obligations under the Single Convention. He concluded that Section 201(d), 21 U.S.C. § 811(d), gave him sole authority over the scheduling of substances controlled by treaty, without regard to the referral and rulemaking procedures specified in Section 201(a)-(c). Id. at 18098.
NORML filed a petition for review with this court and, on January 15, 1974, the court reversed and remanded for consideration on the merits. National Organization for Reform of Marijuana Laws (NORML) v. Ingersoll, 162 U.S.App.D.C. 67, 497 F.2d 654 (1974). The court’s opinion inveighed against an agency’s outright rejection of the filing of a petition, except in narrowly circumscribed situations:
In this case there is no procedural defect or failure to comply with a clear-cut requirement of law. What accounted for respondent’s action is his conclusion on the merits that the petition sought action inconsistent with treaty commitment. * * * That kind of determination should have been reflected in an action denying the petition on the merits * s(c sfc Hf *
Id. at 72, 497 F.2d at 659.
In delineating the areas of interest to be addressed on remand, the court indicated that, in view of the treaty’s exclusion of separated leaves from the terms “cannabis” and “cannabis resin,” the agency should separately consider rescheduling the leaves of the marihuana plant. Id. at 73, 497 F.2d at 660.34 In addition, the court suggested that the proceeding on remand be divided into two phases:
In the first phase, the Department of Justice could consider whether there is any latitude [to reschedule] consistent with treaty obligations, and herein receive expert testimony limited to this treaty issue. The second phase would arise only if some latitude were found, and would consider how the pertinent executive discretion should be exercised.
Id. at 661 n.17. In connection with this “second phase” the court commented on the Director’s argument that under Section 201(d) scheduling of marihuana was a matter entrusted to his sole discretion as delegee of the Attorney General:
This is a matter that gives us pause. The respondent seems to be saying that even though the treaty does not require more control than Schedule V provides, he can on his own say-so and without any reason insist on schedule I. We doubt that this was the intent of Congress.
Id. at 73-74, 497 F.2d at 660-661.35
B. The proceedings on remand.
On June 26, 1974 DEA published a notice in the Federal Register announcing that the [742]*742agency was prepared to hold a hearing to determine the regulatory controls necessary to satisfy the Single Convention. 39 Fed. Reg. 23072 (1974). In response to this notice NORML and the American Public Health Association requested a “phase one” hearing on this issue. They specifically asked that the hearing include an inquiry as to whether separated leaves and/or seeds of the marihuana plant could be removed from CSA Schedule I.
From January 28 through January 30, 1975 a hearing was held before Administrative Law Judge (ALJ) Parker. NORML called two witnesses, Mr. Lawrence Hoover and Dr. Joel Fort, both of whom qualified as experts on the obligations imposed by the Single Convention. Respondent called two chemists, Mr. Philip Porto and Dr. Carlton Turner, as well as DEA’s Chief Counsel, Mr. Donald Miller, who qualified as an expert on the treaty issue.36 The parties introduced numerous exhibits.
On May 21, 1975 ALJ Parker issued his report. Petitioner’s Appendix C. He held that, consistent with the Single Convention, “cannabis” and “cannabis resin”- — as defined by the treaty — could be rescheduled' to CSA Schedule II, cannabis leaves could be rescheduled to CSA Schedule V, and cannabis seeds and “synthetic cannabis”37 could be decontrolled. He rejected respondent’s interpretation of Section 201(d) and held that in the second phase of the rescheduling proceeding the agency should follow the referral and hearing procedures set forth in Section 201(a)-(c). Petitioner’s Appendix C at 31-34.
On appeal from ALJ Parker’s order, DEA’s Acting Administrator,38 Henry S. Dogin, denied NORML’s petition for rescheduling “in all respects.” 40 Fed.Reg. 44164, 44168 (1975). Turning first to the issue of United States treaty commitments, he held that cannabis and cannabis resin could be rescheduled to CSA Schedule II, separated cannabis leaves could be rescheduled to CSA Schedule III or IV,39 synthetic tetrahydrocannabinol (or THC) and seeds incapable of germination need not be controlled, but seeds capable of germination could not be decontrolled. Id. at 44167-44168. He failed to specify the schedule that would satisfy the Single Convention with respect to seeds capable of germination.40 He did hold, however, that neither cannabis seeds incapable of germination nor synthetic THC were at issue in the proceeding. Id. at 44167, 44168.
After outlining the latitude within which various parts of the marihuana plant could be rescheduled, the Acting Administrator proceeded to determine how to exercise his discretion to reschedule. He examined a letter of April 14, 1975 from Dr. Theodore Cooper, Acting Assistant Secretary for Health. The letter, which was introduced at oral argument before ALJ Parker, states that there “is currently no accepted medical use of marihuana in the United States” and that there “is no approved New Drug Application” for marihuana on file with the [743]*743Food and Drug Administration of HEW.41 Relying on this letter, the Acting Administrator concluded that marihuana could not be removed from CSA Schedule I. He stated that Schedule I “is the only schedule reserved for drugs without a currently accepted medical use in treatment in the United States.” Id. at 44167. Because the letter from Dr. Cooper established that marihuana has no medical use, “no matter the weight of the scientific or medical evidence which petitioners might adduce, the Attorney General could not remove marihuana from Schedule I.” Id.
Turning finally to the controversy over the interpretation of Section 201(d), the Acting Administrator stated:
It is unnecessary to decide whether Section 201(d) requires the Attorney General to seek the views of HEW on a substance included in an international treaty. In the instance of marihuana he has done so and he has received a reply.
Id. at 44165.42
C. The present lawsuit.
On October 22, 1975 NORML filed with this court a petition for review of the Act-
ing Administrator’s order. Petitioner urges the court to reverse and remand the case for further proceedings — to include referral of the rescheduling petition to the Secretary of HEW pursuant to Section 201(b)-(c) of the CSA. NORML agrees with ALJ Parker’s conclusions as to the scheduling options left open by the Single Convention, except to the extent that he ruled out rescheduling cannabis and cannabis resin below CSA Schedule II.43
Respondent proffers alternative arguments in defense of the Acting Administrator’s decision to deny NORML’s rescheduling petition and thereby perpetuate placement of marihuana in CSA Schedule I. Respondent alleges first that by virtue of Section 201(d) the referral and hearing procedures of Section 201(a)-(c) do not apply to drugs subject by treaty to international control. Accordingly, the decision whether to reschedule marihuana is entrusted to the Acting Administrator, as delegee of the Attorney General, and the only question open on review is whether his decision not to reschedule the drug is based on substantial evidence. Section 507, 21 U.S.C. § 877.
IV. SCHEDULING DECISIONS UNDER SECTION 201
A. Statutory construction of Section 201(d).
We agree with the parties that the Single Convention leaves some degree of latitude within which to reschedule the various parts of the marihuana plant under the CSA. We defer our discussion of the precise degree of that latitude and turn first to the crucial question confronting the court: interpretation of Section 201(d). We note at the outset that the Acting Administrator declined to decide the issue.45
Section 201(d) provides that if control of a substance is required by United States treaty obligations, “the Attorney General shall issue an order controlling such drug under the schedule he deems most appropriate to carry out such obligations,” without regard to the referral and hearing procedures prescribed by Section 201(a)-(c) and without regard to the Section 202 criteria ordinarily governing scheduling decisions. Each party relies on the language and history of subsection (d) to support its construction of the provision. However, although the report of the House Committee on Interstate and Foreign Commerce does make specific reference to Section 201(d), the statements essentially track the language of the provision and offer little guidance for statutory interpretation.46 Never[745]*745theless, the events surrounding the drafting of Section 201(a)-(d) reveal an overarching congressional aim to limit the Attorney General’s authority to make scheduling judgments under the Act — a goal that militates strongly in favor of petitioner’s interpretation of Section 201(d).
Following extensive debate on the Senate floor, proposals to transfer much of the Attorney General’s scheduling authority to the Secretary of HEW were narrowly defeated.47 However, the bill reported and passed in the House of Representatives incorporated the philosophy of the defeated Senate amendments: The bill required the Attorney General, in making scheduling decisions, to request from the Secretary of HEW his scientific and medical evaluation of the need for control; unlike the Senate bill, the House bill made his recommendations binding on the Attorney General.48 This division of decisionmaking responsibility was fashioned in recognition of the two agencies’ respective areas of expertise. Members of the House repeatedly stated that the Department of Justice should make judgments based on law enforcement considerations, while HEW should have the [746]*746final say with respect to medical and scientific determinations.49 After minor revisions in conference,50 the House version of the bill was signed into law as the Controlled Substances Act of 1970.51
Section 201(d) must be read against this backdrop of intense concern with establishing and preserving HEW’s avenue of input into scheduling decisions. Comments by various congressmen confirm the limited purpose of subsection (d): to authorize the Attorney General to disregard scheduling criteria and HEW recommendations that would otherwise lead to scheduling of a substance in violation of treaty commitments.52 Congress never intended to allow the Attorney General to displace the Secretary whenever any international obligations attach to a particular drug — especially in view of the fact that the vast majority of substances listed in the CSA are controlled by treaty.53 Respondent’s reading of Section 201(d) would destroy a balance of power created by a deliberate and conscientious exercise of the legislative process.
The language of Section 201(d) is consistent with the clear import of the Act’s legislative history. The section provides that the Attorney General shall, without regard to the usual referral and hearing procedures, “issue an order controlling such drug under the schedule he deems most appropriate to carry out such [international] obligations * * *(Emphasis added.) The underscored phrase, which is omitted from the dissent’s discussion of this section, circumscribes the Attorney General’s scheduling authority: it enables him to place a substance in a CSA schedule — without regard to medical and scientific findings— only to the extent that placement in that schedule is necessary to satisfy United States international obligations. Had the provision been intended to grant him unlimited scheduling discretion with respect to internationally controlled substances, it [747]*747would have authorized him to issue an order controlling such drug “under the schedule he deems most appropriate.”
Our interpretation of Section 201(d) ensures proper allocation of decisionmaking responsibility between the Attorney General and the Secretary of HEW, in accordance with their respective spheres of expertise. Section 201(d) directs the Attorney General, as an initial matter, to make a legal judgment as to controls necessitated by international commitments. He then establishes a minimum schedule or level of control below which placement of the substance may not fall. Determination of a minimum schedule ensures that the Secretary’s recommendation, which ordinarily would be binding as to medical and scientific findings, does not cause a substance to be scheduled in violation of treaty obligations. However, once that minimum schedule is established by the Attorney General, the decision whether to impose controls more restrictive than required by treaty implicates the same medical and scientific considerations as do scheduling decisions regarding those few substances not controlled by treaty. The Secretary of HEW is manifestly more competent to make these nonlegal evaluations and recommendations.
Moreover, we think it not insignificant that the Office of Legal Counsel of the Department of Justice, in a memorandum dated August 21,1972,54 adopted the following construction of Section 201(d): The Attorney General is directed to determine the CSA schedule that will satisfy the nation’s obligation under the Single Convention; to the extent that there is latitude to schedule a substance consistent with treaty obligations, “the Attorney General [is] obliged to follow the prescribed procedures in obtaining a medical and scientific evaluation from the Secretary of Health, Education, and Welfare.” Petitioner’s Appendix F at 14. Thus in rejecting DEA’s interpretation of Section 201(d), we embrace the same interpretation urged by staff counsel to DEA’s parent agency, the Department of Justice.55
B. Satisfaction of the referral and hearing procedures of Section 201(a)-(c).
As an alternative argument respondent contends — and the Acting Administrator held — that whatever the proper interpretation of Section 201(d), Dr. Cooper’s letter satisfied the Section 201(b)-(e) requirement that the Acting Administrator refer the petition to the Secretary of HEW for medical and scientific findings and recommendations. The Acting Administrator premised his conclusion on the assumption that placement in CSA Schedule I is automatically required if the substance has no currently accepted medical use in the United States. Our analysis of the Act compels us to reject his finding.
The CSA makes clear that, upon referral by the Attorney General, the Secretary of HEW is required to consider a number of different factors in making his evaluations and recommendations. Section 201(b)-(c) specifies that the Secretary must consider “scientific evidence of [the substance’s] pharmacological effect, if known”; “the state of current scientific knowledge regarding the drug or other substance”; “what, if any, risk there is to the public health”; the drug’s “psychic or physiological dependence liability”; “whether the substance is an immediate precursor of a substance already controlled under this sub-chapter”; and any scientific or medical fac[748]*748tors relating to the drug’s “actual or relative potential for abuse,” its “history and current pattern of abuse,” and “scope, duration, and significance of abuse.” The provision does not in any way qualify the Secretary’s duty of evaluation.56 If, as respondent contends, a determination that the substance has no accepted medical use ends the inquiry, then presumably Congress would have spelled that out in its procedural guidelines. Its failure to do so indicates an intent to reserve to HEW a finely tuned balancing process involving several medical and scientific considerations. By shortcut-ting the referral procedures of Section 201(b)-(c) the Acting Administrator precluded the balancing process contemplated by Congress.
Admittedly, Section 202(b), 21 U.S.C. § 812(b), which sets forth the criteria for placement in each of the five CSA schedules, established medical use as the factor that distinguishes substances in Schedule II from those in Schedule I. However, placement in Schedule I does not appear to flow inevitably from lack of a currently accepted medical use. Like that of Section 201(c), the structure of Section 202(b) contemplates balancing of medical usefulness along with several other considerations, including potential for abuse and danger of dependence.57 To treat medical use as the controlling factor in classification decisions is to render irrelevant the other “findings” required by Section 202(b). The legislative history of the CSA indicates that medical use is but one factor to be considered, and by no means the most important one.58
Moreover, DEA’s own scheduling practices support the conclusion that substances lacking medical usefulness need not always be placed in Schedule I. At the hearing before ALJ Parker DEA’s Chief Counsel, Donald Miller, testified that several substances listed in CSA Schedule II, including poppy straw, have no currently accepted medical use. Tr. at 473-474, 488. He further acknowledged that marihuana could be rescheduled to Schedule II without a currently accepted medical use. Tr. at 487-488. Neither party offered any contrary evidence.
More importantly, even if lack of medical use is dispositive of a classification [749]*749decision, we do not think the finding in this case was established in conformity with the statute. Dr. Cooper’s letter is addressed to a member of DEA’s legal staff, in response to the latter’s inquiry; the letter was not solicited by the Acting Administrator, and it can hardly take the place of the elaborate referral machinery contemplated by Congress.59 The one-page letter makes conclusory statements without providing a basis for or explanation of its findings.60 It is unclear what Dr. Cooper means when he writes that marihuana has no currently accepted medical use. As a legal conclusion, his statement cannot be doubted: Placement in Schedule I creates a self-fulfilling prophecy, Tr. at 170, because the drug can be used only for research purposes, Tr. at 488, and therefore is barred from general medical use. But if Dr. Cooper’s statement is meant to reflect a scientific judgment as to the medicinal potential of marihuana, then the basis for his evaluation should be elaborated. Recent studies have yielded findings to the contrary:61 HEW’s Fifth Annual Report to the U.S. Congress, Marihuana and Health (1975), devotes a chapter to the therapeutic aspects of marihuana, discovered through medical research. Id. ch. 9, at 117-127. Possible uses of marihuana include treatment of glaucoma,62 asthma, and epilepsy, and provision of “needed relief for cancer patients undergoing chemotherapy.” Id. at 117. These promising findings were discussed by Dr. Fort in his testimony before ALJ Parker. Tr. at 163-165, 169-170. Only a formal referral and hearing will allow due weight to be given to such findings.63 Accordingly, recognizing that it is our obligation as a court to ensure that the agency acts within statutory bounds,64 we hold that Dr. Coo[750]*750per’s letter was not an adequate substitute for the procedures enumerated in Section 201(a)-(c).65 The case must be remanded for further proceedings consistent with those statutory requirements.
V. CONTROLS REQUIRED BY THE SINGLE CONVENTION
We turn now to a discussion of the scheduling options left open by the Single Convention.
A. Cannabis and cannabis resin.
The Single Convention defines “cannabis” as the fruiting or flowering tops of the cannabis plant, including leaves when not detached, Art. 1, 111(b), and “cannabis resin” as any resin that has been extracted from the plant. Art. 1, U 1(d). These “drugs” are listed in Schedules I and IV of the treaty and are therefore subject to severe restrictions on manufacturing, distribution, and international trade.66 Nevertheless, the parties agree and the Acting [751]*751Administrator held67 that cannabis and cannabis resin could be rescheduled to CSA Schedule II consistent with the Single Convention.68
Comparison of the control regimes of the CSA and the Single Convention reveals the rationality of this consensus. The primary difference between substances in CSA Schedule I and those in Schedule II is that the former may be used for research only, whereas the latter may be prescribed by licensed physicians. Tr. at 488.69 Nothing in the Single Convention requires that cannabis and cannabis resin be limited to research. In Art. 2, 115 the treaty provides several open-ended guidelines applicable to Schedule IV drugs such as cannabis and cannabis resin. For example, a nation must limit production of, trade in, and use of a Schedule IV substance for research purposes “if in its opinion the prevailing conditions in its country render it the most appropriate means of protecting the public health and welfare * * *Art. 2, K 5(b). In a similar vein, Art. 2, K 5(a) provides that a nation must “adopt any special measures of control which in its opinion are necessary having regard to the particularly dangerous properties of a drug so included * * *The official interpretation of the Single Convention, Commentary on the Single Convention on Narcotic Drugs, 1961 (“Commentary”), prepared by the Secretary-General of the United Nations, states that the only requirement imposed by these provisions is that the party act in good faith in determining whether any special measures are needed with regard to Schedule IV drugs. Petitioner’s Appendix E at 65. ALJ Parker correctly held that under this standard the United States could decline to restrict cannabis and cannabis resin to research purposes and could reschedule the drugs to CSA Schedule II.70 Neither respondent nor the Acting Administrator contests this conclusion.
The parties further agree that, without imposition of additional restrictions on lower schedules, CSA Schedule II is necessary as well as sufficient to satisfy our international obligations. Petitioner’s br. at 30, 35; respondent’s br. at 12. As detailed in ALJ Parker’s Findings, petitioner’s Appendix C at 22-24, several requirements imposed by the Single Convention would not be met if cannabis and cannabis resin were placed in CSA Schedule III, IV or V.71 NORML con[752]*752cedes this point; however, it argues that the delegee of the Attorney General could place the substances in a less restrictive schedule provided he exercised his rulemaking authority to impose additional restrictions to satisfy the Single Convention.72 Petitioner’s br, at 35-41. ALJ Parker rejected this argument, expressing some reservations as to whether the Attorney General had the authority to promulgate such rules. Petitioner’s Appendix C at 25-26. Respondent agrees with ALJ Parker, adding that “[pjetitioner’s request, that DEA create a new schedule for marihuana, is beyond the scope of DEA’s authority under the Act.” Respondent’s br. at 12. The Acting Administrator sidestepped the issue by concluding that a lack of currently accepted medical use mandates that marihuana remain in CSA Schedule I. 40 Fed.Reg. 44167, 44168 (1975).
This court need not decide whether the Attorney General’s rulemaking authority permits creation of a hybrid classification. In the circumstances of this case, Section 201(d) plainly authorizes him to decline to promulgate the rules suggested by petitioner. NORML ignores the language of that section, which directs the Attorney General to issue an order controlling a substance “under the schedule he deems most appropriate to carry out” United States international obligations. Even under a narrow reading of subsection (d), the Attorney General — to satisfy treaty requirements — is directed to establish a minimum schedule below which the substance in question may not be placed. Establishment of this minimum schedule is based on a legal judgment as to the controls mandated by the Single Convention, and need not be justified by medical and scientific findings.
Petitioner’s request for special rulemaking undercuts the language and purpose of Section 201(d). If, as NORML suggests, the Attorney General must consider whether a substance controlled by treaty can be placed in a less restrictive CSA schedule provided additional requirements are imposed through the rulemaking process, then Congress would not have authorized him to place the substance in the schedule he deems most appropriate to carry out our treaty obligations. If Section 201(d) is to have any meaning at all, it must be read to authorize placement of cannabis and cannabis resin in CSA Schedule II, despite the fact that a specially imposed combination of controls might meet the requirements of the Single Convention. Congress surely did not intend to require the Attorney General to consider creation of a hybrid schedule each time an interested party files a petition to reschedule a substance controlled by treaty.
B. Cannabis leaves (when unaccompanied by the tops).
NORML contends that ALJ Parker was correct in finding that under the Single Convention cannabis leaves may be rescheduled to CSA Schedule V. Respondent defends the Acting Administrator’s conclusion that cannabis leaves may be rescheduled to CSA Schedule III or IV but not to Schedule V. See 40 Fed.Reg. 44167, 44168 (1975).
As noted earlier, Art. 28, H 3 contains the treaty’s only reference to separated cannabis leaves. That provision states that “[t]he Parties shall adopt such measures as may be necessary to prevent the misuse of, and illicit traffic in, the leaves of the cannabis plant.” Petitioner’s and respondent’s expert witnesses both agreed that the treaty leaves to the discretion of each country the determination of measures necessary to prevent misuse and illicit traffic.73 Tr. at 43, 48, 127, 415, 445, 452. ALJ Parker conclud[753]*753ed that “any measures which the United States adopted when, viewed objectively, amounted to a good faith effort to prevent the ‘misuse of, and illicit traffic in, the leaves of the cannabis plant’ * * * would satisfy our obligations under the Convention.” Petitioner’s Appendix C at 28. The Acting Administrator added that a good faith effort would have to be “our best effort.” 40 Fed.Reg. 44166 (1975).
The major difference between substances placed in CSA Schedule IV and those placed in Schedule V is that under Section 309, 21 U.S.C. § 829, the former may be dispensed only by prescription. The Single Convention does not require that cannabis leaVes be dispensed only by prescription.74 In fact, the Commentary to the treaty provides:
Parties are not bound to prohibit the consumption of the leaves for non-medical purposes,[75] but only to take the necessary measures to prevent their misuse. This might involve an obligation to prevent the consumption of very potent leaves, or of excessive quantities of them. It may be assumed that Parties would in any case not be permitted by paragraph 3 to authorize the uncontrolled use of the leaves. Any authorized consumption would have to be governed by such regulations as would be required to prevent illicit traffic and misuse.[76] The conditions under which non-medical consumption might be permitted might also depend on the outcome of the studies which at the time of this writing are being carried out concerning the effects of the use of the leaves.
Petitioner’s Appendix E at 316. Moreover, the history of the treaty provision in question indicates that countries are given much leeway in determining what is “misuse of” and “illicit traffic in” cannabis leaves and in fashioning methods of preventing these two evils.77
Given the background of the relevant treaty provisions, we conclude that the Single Convention would allow the United States to place separated marihuana leaves in CSA Schedule V. The Acting Administrator agreed with this conclusion as an abstract legal principle; however, he broadened the inquiry and held that, in any event, he would not exercise his discretion to transfer marihuana leaves from CSA Schedule I to Schedule V. Specifically, he stated:
* * * If the Acting Administrator were faced with this question in the framework of an academic discussion, he might agree that Schedule V controls [754]*754could technically so limit separated leaves (and seeds capable of germination) as to meet the bare bones language of the treaty.
However, marihuana in the illicit traffic is a mixture of crushed leaves, flowers, and twigs, and THC can be extracted from the leaves to make hash oil. Thus, the misuse to which the leaves can be put and the form in which marihuana appears illicitly, make it obvious that Schedule V controls, which permit over-the-counter sales for a “medical purpose” would fall far short of the contemplated restrictions and purposes of the Single Convention and the intent of the Comprehensive Drug Abuse Prevention and Control Act of 1970.
40 Fed.Reg. 44167 (1975); see id. at 44168.
The Acting Administrator’s determination that CSA Schedule V controls are inadequate because of the usual composition of “marihuana” in this country is not, strictly speaking, a judgment regarding the degree of control mandated by the terms of the treaty. Indeed, the treaty itself makes a distinction between cannabis and separated cannabis leaves.78 Accordingly, this court must decide whether to uphold the Acting Administrator’s decision as an exercise of his discretion within the latitude allowed by the treaty.
Whatever the relevance of marihuana mixtures in this country,79 we find that the Acting Administrator acted prematurely in making his determination. According to the procedures set out in Section 201(a)-(c) of the CSA, the Acting Administrator should first have referred the rescheduling petition to HEW for its binding scientific and medical evaluations and recommendations. Those recommendations would have set the upper limits of the Acting Administrator’s discretion to reschedule. The issue could then have been fully litigated at a DEA rulemaking hearing.80 At that point in the proceedings the Acting Administrator would have been in a far better position to make an informed determination.81 The Acting Administrator’s determination in this case was not made in conformity with Section 201(a)-(c). We owe no deference to a statutorily invalid exercise of discretion.82
[755]*755C. Cannabis seeds (when unaccompanied by the tops).
Cannabis seeds detached from the tops are not included within the treaty’s definition of “cannabis.” None of the controls outlined in the treaty refers specifically to cannabis seeds. The only arguably relevant provision is Art. 2, 18, which provides:
The Parties shall use their best endeavors to apply to substances which do not fall under this Convention, but which may be used in the illicit manufacture of drugs, such measures of supervision as may be practicable.
The Commentary to this provision states that “[t]he vagueness of the wording of paragraph 8 leaves it practically to the discretion of each Party to decide to what substances it should apply the control provided in this paragraph, and what measures it would be practicable to take.” Petitioner’s Appendix E at 71.
NORML contends — and ALJ Parker agreed — that the treaty allows decontrol of cannabis seeds. In his published opinion the Acting Administrator took the position that seeds incapable of germination are not covered by the treaty,83 but that seeds capable of germination are covered and may not be decontrolled. 40 Fed.Reg. 44167 (1975). Respondent agrees that under Art. 2, K8 “[i]t would be a violation of the Single Convention to allow seeds which can produce cannabis plants to be free from control.” Respondent’s br. at 14. Neither the Acting Administrator’s opinion nor respondent’s brief specifies the precise degree of control necessary to satisfy the treaty.84
We are not persuaded that the Acting Administrator erred in concluding that Art. 2, H 8 creates an affirmative duty to establish some measure of control over cannabis seeds capable of germination. In acknowledging the discretion of each nation to determine those substances embraced by Art. 2, H 8 and the practicability of various measures of supervision, the Commentary assigns a specific purpose to the open-endedness of the provision. First, the drafters of the treaty could not foresee which substances would in the future be used in illicit manufacture of narcotic drugs: “It is this impossibility to foresee the substances which might require the application of control measures which led to the adoption of this very broad and vague provision.” Petitioner’s Appendix E at 71. Second, the Single Convention recognizes that measures practicable in one country may be impracticable in another, where the substance is used for legitimate industrial purposes, id.; thus the treaty confers broad discretion to adopt “such measures of supervision as may be practicable.”
The Acting Administrator’s conclusion that the United States cannot decontrol cannabis seeds capable of germination is [756]*756consistent with the purposes of the discretionary aspects of Art. 2, 1 8. It cannot be doubted that seeds capable of germination are currently used and will continue to be used in illicit manufacture of cannabis materials; hence, no problem of foreseeability is involved. Nor does petitioner contend that the seeds have some legitimate purpose that would be frustrated by imposition of any degree of control.85 In these circumstances, we affirm the Acting Administrator’s finding that Art. 2, K2 contemplates some measure of control over cannabis seeds capable of germination.
The Acting Administrator further found, “in the framework of an academic discussion,” that CSA Schedule V controls over seeds capable of germination would meet the requirements of the Single Convention. 40 Fed.Reg. 44167 (1975), Given the open-ended nature of Art. 2,18 and the limitations attaching to CSA Schedule V substances,86 we agree that placement in the least restrictive domestic schedule would not violate the letter or spirit of the treaty. However, at this stage of the proceeding we are constrained to reject the Acting Administrator’s implication that marihuana mixtures in this country necessitate more restrictive controls over cannabis seeds. 40 Fed.Reg. 44167 (1975).87 The Acting Administrator’s finding, like that regarding cannabis leaves, should have been deferred until after compliance with the referral and hearing requirements of Section 201(a)-(c).
D. Synthetic tetrahydrocannabinol (THC) or “artificial cannabis.”
The synthetic equivalents of marihuana extracts, tetrahydrocannabinols (THC),88 are contained in CSA Schedule I.89 In his discussion of United States treaty obligations ALJ Parker correctly held that neither the Single Convention nor any other treaty to which this country is a party requires control of synthetic THC.90 Petitioner’s Appendix C at 14. The Acting Administrator agreed that synthetic THC is not controlled by treaty, but added that it therefore is not “in issue” in this proceeding. 40 Fed.Reg. 44167 (1975).
The lack of treaty obligations with respect to synthetic THC means only that the nation retains unlimited latitude within which to schedule the drug under the Controlled Substances Act91; that finding in no way leads to the conclusion that synthetic THC is not “in issue.” Respondent, however, takes a somewhat different position, arguing that synthetic THC is not in issue because no petition to reschedule the drug has yet been filed. Respondent’s br. at 18. Relying on ALJ Parker’s finding, petitioner responds that, although not listed in the initial request for a hearing, synthetic THC was put in issue without objection through the hearing testimony. Petitioner’s br. at [757]*75750-52 (citing petitioner’s Appendix C at 15). See Tr. at 49, 86, 471. Petitioner adds that since the parties concur that no international controls exist, see respondent’s br. at 18, the question of rescheduling synthetic THC should be “referred to the Secretary of HEW as a separate category of cannabis material.” Petitioner’s br. at 51.
We note at the outset that DEA does not contend that it was prejudiced when the issue of synthetic THC was raised at the hearing; indeed, in accord with the hearing testimony, respondent readily concedes that the Single Convention does not apply to the substance. Nor does respondent argue that the similarities between synthetic THC and natural marihuana materials are too slight to warrant consolidated consideration. The sole reason for DEA’s opposition to consideration of rescheduling THC is NORML’s failure to have filed the appropriate petition with the agency. However, under both CSA Section 201 and the applicable regulations, see 21 C.F.R. §§ 1308,1316, it appears that a petition to reschedule may be filed at any time.92 We therefore conclude that, in the interest of justice and in furtherance of a final resolution of this protracted controversy, NORML should be allowed either to amend its earlier petition or to file a new petition requesting that synthetic THC be rescheduled. The ensuing proceeding should be consolidated with the proceeding to reschedule natural cannabis materials.
VI. CONCLUSION
This case is remanded for further proceedings not inconsistent with this opinion. Specifically, the Acting Administrator is directed, pursuant to Section 201(a)-(c), to refer the NORML petition to the Secretary of HEW for medical and scientific findings and recommendations for rescheduling, consistent with the requirements of the Single Convention, as interpreted by this court. The Secretary of HEW is directed to make separate evaluations and recommendations for each of the following cannabis materials, within the limits authorized by treaty:
1. “Cannabis” and “cannabis resin” (minimum control regime of CSA Schedule II).
2. Cannabis leaves (minimum control regime of Schedule V).
3. Cannabis seeds capable of germination (minimum control regime of Schedule V).
4. Synthetic THC (no minimum control regime).
Following receipt of the Secretary’s evaluations and recommendations, the Acting Administrator is directed to comply with the rulemaking procedures outlined in Section 201(a)-(b).
So ordered.
Appendix to follow.
[758]*758APPENDIX
From Vodra, The Controlled Substances Act, DRUG ENFORCEMENT, Vol. 2, No. 2, at 20-21 (Spring 1975).
Control Mechanisms.of the CSA SCHEDULE REGISTRATION RECORD-KEEPING MANUFACTURING QUOTAS DISTRIBUTION RESTRICTIONS DIS-PENS-ING LIMITS IMPORT-EXPORT NONNARCOTIC SE-CUR-ITY MANUFACTURER/ DISTRIBUTOR REPORTS TO PEA CRIMINAL PENALTIES FOR TRAFFICKING (FIRST OFFENSE) NONNARCOTIC Required Separate Order forms Research use only Vault type Yes 15 years/ $25,000 5 years/ $15,000 Required Separate Order forms Rx: written; no refills Vault type 15 years/ $25,000 5 years/ $15,000 Required Readily retrievable No but Some drugs* limited by Schedule IX quotas DEA registration number Rx: written or oral with medical authorization; refills up to 5 times in 6 months Surveil-lance Yes Narcotic 5 years/ $15,000 No Nonnarcotic 5 years/ $15,000 Required Readily retrievable No but Some drugs* limited by Schedule XI quotas DEA registration number Rx: . written or oral with medical authorization; refills . up to 5 times in 6 months Surveil-lance No Narcotic 3 years/ $10,000 No Nonnarcotic 3 years/ $10,000 Required Readily retrievable No but Some drugs* limited by Schedule XX quotas DEA registration number 0TC (Rx drugs limited Co MD's order) import Surveil-lance Manufacturer only. Narcotic l year/ $5,000 those derived from substances in/Schedule II export NO Nonnarcotic 1 year/ $5,000
75. Art. 4, H (c) requires the parties to limit production, distribution, possession, and use of drugs to medical and scientific purposes. Separated leaves are not “drugs” and therefore are not subject to this restriction.