The criminal reproachability differs between substances that cause (opium, cocaine, ...) and those that do not cause serious damage to health (cannabis and derivatives). It is considered a crime of danger (abstract risk), so it is not necessary to make the drug available to third parties for its criminalization.
Indications that lead to think that there is a final destination for trafficking: The Supreme Court has collected certain indications that lead to thinking that there is a final destination for trafficking through the amount of drug possessed (Non-jurisdictional Agreement of the Plenary of October 19, 2001 assumes the table of the National Institute of Toxicology on the average daily consumption dose), the way in which it is possessed, possession of devices used to prepare the drug for its distribution, possession of the drug in doses, seizure of money without reason and its accounting, transfer of people in a short period of time,....
Possession for shared consumption: Possession for shared consumption is atypical due to the lack of risk to public health. It is included in the doctrine of the TS (addicted consumers, in a closed place, insignificant quantity, certain and determined persons, without remunerative consideration). Cannabis associations (STS Plenary 7/9/15)
There are mitigating factors for repentance or collaborating with the Administration of Justice or for being a drug addict at the time of the commission of the act for which it will be necessary to prove detoxification and that the amount is not excessively serious.