These drugs are usually known in the UK as controlled drugs, because they are such by the meaning given to that term by the act itself. In more general terms, however, many of these drugs are also controlled by the Medicines Act 1968, and there are many other drugs which are controlled by the Medicines Act but not by the Misuse of Drugs Act.
The Misuse of Drugs Act sets out three separate categories, Class A, Class B, and Class C. Class A drugs represent those deemed most dangerous, and so carry the harshest punishments. Class C represents those thought to have the least capacity to harm, and so the Act demands more lenient punishment. Being found in possession of a drug on this list is dealt with less seriously than would be if it were deemed that there is intent to supply the drug to others.Possession with intent to supply carries a maximum penalty of life imprisonment.
With regard to lawful possession and supply, a different set of categories apply which are set out in the Misuse of Drugs Regulations 2001 (as amended). This sets out five schedules each with their own restrictions. Schedule 1 contains substances with no medicinal value such as hallucinogens and their use is limited primarily to research, whereas schedules 2-5 contain the other regulated drugs. This means that although drugs may fall into the category of Class A/B/C, they may also fall into one of the schedules for legitimate medicinal use. For example, morphine is a Class A drug under the Misuse of Drugs Act 1971, but when lawfully supplied falls under the category of a Schedule 2 controlled drug.