[3] Since the Single Convention is not self-executing, parties must enact legislation to carry out its provisions, and the UNODC works with countries' legislatures to ensure compliance.

According to a 1954 interview with United States Commissioner of Narcotics Harry J. Anslinger, the cumbersome process of conference and state-by-state ratification could take many decades.

[5] A Senate of Canada committee reported: "The work of consolidating the existing international drug control treaties into one instrument began in 1948, but it was 1961 before an acceptable third draft was ready.

[8] The legal commentary was written by the United Nations Secretary-General staff member Adolf Lande, the former Secretary of the Permanent Central Narcotics Board and Drug Supervisory Body, operating under a mandate to give "an interpretation of the provisions of the Convention in the light of the relevant conference proceedings and other material.

The conference met at the United Nations Office at Geneva from 6 to 24 March 1972, producing the 1972 Protocol Amending the Single Convention on Narcotic Drugs.

The Preamble to this treaty acknowledges the inadequacy of the Single Convention's controls to stop "steadily increasing inroads into various social groups made by illicit traffic in narcotic drugs and psychotropic substances".

The new treaty focuses on stopping organized crime by providing for international cooperation in apprehending and convicting gangsters and starving them of funds through forfeiture, asset freezing, and other methods.

Article 49 allows countries to phase out coca leaf chewing, opium smoking, and other traditional drug uses gradually, but provides that "the use of cannabis for other than medical and scientific purposes must be discontinued as soon as possible".

"[21] Article 36 requires Parties to adopt measures against "cultivation, production, manufacture, extraction, preparation, possession, offering, offering for sale, distribution, purchase, sale, delivery on any terms whatsoever, brokerage, dispatch, dispatch in transit, transport, importation and exportation of drugs contrary to the provisions of this Convention," as well as "[i]ntentional participation in, conspiracy to commit and attempts to commit, any of such offences, and preparatory acts and financial operations in connexion with the offences referred to in this article", but it does not directly require criminalization of all the above; it states only in the cases of (unspecified) serious offences that they "shall be liable to adequate punishment particularly by imprisonment or other penalties of deprivation of liberty."

A 1972 amendment to the Article grants nations the discretion to substitute "treatment, education, after-care, rehabilitation and social reintegration" for criminal penalties if the offender is a drug abuser.

However, the Ministry of Health, Welfare and Sport's report, Drugs Policy in the Netherlands, notes that large-scale "[p]roduction and trafficking are dealt with severely under the criminal law, in accordance with the UN Single Convention.

"[23] Some of the most severe penalties for drug trafficking are handed down in certain Asian countries, such as Malaysia, which mandate capital punishment for offenses involving amounts over a certain threshold.

[24] Most nations, such as France and the United States, find a middle ground, imposing a spectrum of sanctions ranging from probation to life imprisonment for drug offenses.

This is a reasonable inference from the terms of Article 4, which obliges the parties "to limit exclusively to medical and scientific purposes the production, manufacture, export, import, distribution of, trade in, use and possession of drugs".

[26]The Canadian Department of National Health and Welfare's 1979 report, The Single Convention and Its Implications for Canadian Cannabis Policy, counters with circumstantial evidence to the contrary:[27] The substantive argument in support of simple possession falling outside the scope of Article 36 is founded on the assumption that it is intended to insure a penal response to the problem of illicit trafficking rather than to punish drug users who do not participate in the traffic.

(See United Nations, 1973:112; Noll, 1977:44–45) The Third Draft of the Single Convention, which served as the working document for the 1961 Plenipotentiary Conference, contained a paragraph identical to that which now appears as Article 36, subparagraph 1(a).

Further, the Commentary notes that parties which interpret Article 36 as requiring a punitive legal response to simple possession, may undoubtedly choose not to provide for imprisonment of persons found in such possession, but to impose only minor penalties such as fines or even censure (since possession of a small quantity of drugs for personal consumption may be held not to be a serious offense under article 36... and only a serious offense is liable to adequate punishment particularly by imprisonment or other penalties of deprivation of liberty).The Bulletin on Narcotics attempted to tackle the question in 1977:[28] Since some confusion and misunderstanding had existed in the past and some instances still persist in respect of the legal position laid down in the international treaties concerning the relationship between penal sanctions and drug abuse, some clarifying remarks are called for.

From the contents of this provision it is clear that use of drugs and their possession for personal consumption has also to be limited by legislation and administrative measures exclusively to medical and scientific purposes.

[31] Once on a path to reduction, there are now an increasing number of countries worldwide which are returning to hemp cultivation, often a traditional crop in various regions of the world, according to a report of the United Nations Conference on Trade and Development.

From 1931 to 1961, most of the families of synthetic opioids had been developed, including drugs related to methadone, pethidine (meperidine/Demerol), morphinans, and dextromoramide (Palfium, Palphium, Jetrium, Dimorlin, marketed solely in the Netherlands).

The Single Convention, adopted in 1961, consolidated those treaties and broadened their scope to include cannabis and other substances with effects similar to drugs already covered.

Under certain circumstances, Parties are required to limit Schedule IV drugs to research purposes only: (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.The Commentary explains two situations in which this provision would apply: For a considerable period of time – and still at the time of writing – there has been no significant diversion of legally manufactured drugs from legal trade into illicit channels; but if a Government were unable to prevent such a diversion of drugs in Schedule IV, a situation would arise in which the measures of prohibition mentioned in subparagraph (b) would be "the most appropriate means of protecting the public health and welfare".

It may however be assumed that such a situation could rarely if ever arise.The Commentary notes that "Whether the prohibition of drugs in Schedule IV (cannabis and resin, desomorphine, heroin, ketobemidone) should be mandatory or only recommended was a controversial question at the Plenipotentiary Conference."

However, according to the Commentary:[38] The Office of Legal Affairs of the United Nations ruled, in an opinion given to the Commission on Narcotic Drugs at its twenty-third session, that barbiturates, tranquillizers and amphetamines were outside the scope of the Single Convention.

[42] Furthermore, the provisions of the Single Convention regarding the national supply and demand of opium to make morphine contribute to the global shortage of essential poppy-based pain relief medicines.

[45] There has long been a controversy over whether cannabis is "particularly liable to abuse and to produce ill effects" and whether that "liability is not offset by substantial therapeutic advantages", as required by Schedule IV criteria.

Article 21 provides that "the total of the quantities of each drug manufactured and imported by any country or territory in any one year shall not exceed the sum of" the quantity: Article 21 bis, added to the treaty by a 1971 amendment, gives the INCB more enforcement power by allowing it to deduct from a nation's production quota of cannabis, opium, and coca the amounts it determines have been produced within that nation and introduced into the illicit traffic.

[55] In this way, the INCB can essentially punish a narcotics-exporting nation that does not control its illicit traffic by imposing an economic sanction on its medicinal narcotics industry.

Countries are under an obligation not to exceed the amounts of the estimates confirmed or established by the INCB.Article 14 authorizes the INCB to recommend an embargo on imports and exports of drugs from any noncompliant nations.

Germany, the Netherlands, Switzerland, and Spain continue to experiment with medically supervised injection rooms, despite the INCB's objections that the Single Convention's allowance of "scientific purposes" is limited to clinical trials of pharmaceutical grade drugs and not public health interventions.