The first Opium Law was created to regulate drugs with a high addiction or abuse factor, or that are physically harmful.
As the name indicates the main reason for introduction was to regulate the Opium trade and later to control various other addictive drugs like morphine, cocaine, heroin, barbiturates, amphetamines and several decades later, benzodiazapines, which were used both medically and recreationally.
In 1980, the decision to not prosecute cannabis and hashish dealers, under certain conditions, was publicly announced by the Dutch government.
[2][3][4] The following drugs and intermediates are classified as List I drugs of the Opium Law: The esters and derivatives of ecgonine, which can be turned into ecgonine and cocaine; The mono- and di-alkylamide-, the pyrrolidine- and morpholine derivatives of lysergic acid, and the thereby introduction of methyl-, acetyl- or halogen groups obtained substances; Fiveworthy nitrogen-substituted morphinederivates, of which morphine-N-oxide-derivatives, like codeine-N-oxide; The isomers and stereoisomers of tetrahydrocannabinol; The ethers, esters and enantiomers of the above mentioned substances, with exception of dextromethorphan (INN) as enantiomer of levomethorphan and racemethorphan, and with exception of dextrorphanol (INN) as enantiomere of levorphanol and racemorphan; Formulations which contain one or more of the above mentioned substances.
For example, nearly all opioids are List I drugs, but they are commonly prescribed to cancer and HIV patients, as well as sufferers of chronic pain.