It was passed by the 91st United States Congress as Title II of the Comprehensive Drug Abuse Prevention and Control Act of 1970 and signed into law by President Richard Nixon.

[2][3] Classification decisions are required to be made on criteria including potential for abuse (an undefined term),[4] currently accepted medical use in treatment in the United States, and international treaties.

[5][6][7] The Pure Food and Drug Act (1906) was the beginning of over 200 laws concerning public health and consumer protections.

The actual and potential harm of use of the drug is not great enough to justify intrusion by the criminal law into private behavior, a step which our society takes only with the greatest reluctance.

[12]Rufus King notes that this stratagem was similar to that used by Harry Anslinger when he consolidated the previous anti-drug treaties into the Single Convention and took the opportunity to add new provisions that otherwise might have been unpalatable to the international community.

[13] According to David T. Courtwright, "the Act was part of an omnibus reform package designed to rationalize, and in some respects to liberalize, American drug policy."

(Courtwright noted that the Act became, not libertarian, but instead repressionistic to the point of tyrannical in its intent; a cruel and/or arbitrary exercise of power).

[14] King notes that the rehabilitation clauses were added as a compromise to Senator Harold Hughes, who favored a moderate approach.

Subchapter I defines Schedules I–V, lists chemicals used in the manufacture of controlled substances, and differentiates lawful and unlawful manufacturing, distribution, and possession of controlled substances, including possession of Schedule I drugs for personal use; this subchapter also specifies the dollar amounts of fines and durations of prison terms for violations.

Subchapter II describes the laws for exportation and importation of controlled substances, again specifying fines and prison terms for violations.

§ 811(h) allows the Attorney General to temporarily place a substance in Schedule I "to avoid an imminent hazard to the public safety".

Both the CSA and the treaties set out a system for classifying controlled substances in several schedules in accordance with the binding scientific and medical findings of a public health authority.

In Reid v. Covert the Supreme Court of the United States addressed both these issues directly and clearly holding: [N]o agreement with a foreign nation can confer power on the Congress, or on any other branch of Government, which is free from the restraints of the Constitution.

It would not be contended that it extends so far as to authorize what the Constitution forbids, or a change in the character of the government, or in that of one of the States, or a cession of any portion of the territory of the latter, without its consent."

It would be completely anomalous to say that a treaty need not comply with the Constitution when such an agreement can be overridden by a statute that must conform to that instrument.

§ 811(d), which also establishes mechanisms for amending international drug control regulations to correspond with HHS findings on scientific and medical issues.

If the Secretary agrees with the commission's scheduling decision, he can recommend that the Attorney General initiate proceedings to reschedule the drug accordingly.

In 1999, an FDA official explained to Congress: Rohypnol is not approved or available for medical use in the United States, but it is temporarily controlled in Schedule IV pursuant to a treaty obligation under the 1971 Convention on Psychotropic Substances.

At the time flunitrazepam was placed temporarily in Schedule IV (November 5, 1984), there was no evidence of abuse or trafficking of the drug in the United States.

[28]The Cato Institute's Handbook for Congress calls for repealing the CSA, an action that would likely bring the United States into conflict with international law, were the United States not to exercise its sovereign right to withdraw from and/or abrogate the Single Convention on Narcotic Drugs and/or the 1971 Convention on Psychotropic Substances prior to repealing the Controlled Substances Act.

According to former United Nations Drug Control Programme Chief of Demand Reduction Cindy Fazey, "This has been used by the USA not to implement part of article 3 of the 1988 Convention, which prevents inciting others to use narcotic or psychotropic drugs, on the basis that this would be in contravention of their constitutional amendment guaranteeing freedom of speech".

[31] The specific classification of any given drug or other substance is usually a source of controversy, as is the purpose and effectiveness of the entire regulatory scheme.

The term does not include distilled spirits, wine, absinthe, malt beverages, nicotine or tobacco, as those terms are defined or used in subtitle E of the Internal Revenue Code of 1986.Some have argued that this is an important exemption, since alcohol and tobacco are two of the most widely used drugs in the United States.

Schedule II substances are those that have the following findings: Except when dispensed directly to an ultimate user by a practitioner other than a pharmacist, no controlled substance in Schedule II, which is a prescription drug as determined under the Federal Food, Drug, and Cosmetic Act (21 USC 301 et seq.

Schedule III substances are those that have the following findings: Except when dispensed directly by a practitioner, other than a pharmacist, to an ultimate user, no controlled substance in Schedule III or IV, which is a prescription drug as determined under the Federal Food, Drug, and Cosmetic Act (21 USC 301 et seq.

The DEA list of chemicals is actually modified when the United States Attorney General determines that illegal manufacturing processes have changed.

This law requires[59] customer signature of a "log-book" and presentation of valid photo ID in order to purchase PSE-containing products from all retailers.

The definition of what 'analogue' means is kept deliberately vague, presumably to make it harder to circumvent this rule, as it's not clear what is / is not controlled, thus placing an element of risk and deterrent in those performing the supply.

These have the advantage of clearly defining what is controlled, making prosecutions easier and compliance by legitimate companies simpler.

However the downside is that these tend to be harder to understand for non-chemists and also give those wishing to supply for illegitimate reasons something to 'aim' for in terms of non-controlled chemical space.