A second chance, rather than immediate dismissal based upon what may be a single mistake?
The drugs laws of the nation make little sense, made to protect the public, but in practice making things worse through exposure to crime, contaminants in the substances, financing organised crime and terrorism. The Portuguese approach, treating drugs as a health issue, rather than a criminal one has shown much more promise than the ongoing pursuit of criminalisation as the way forward.
The Advisory Council on the Misuse of Drugs and Independent Scientific Committee on Drugs found that alcohol was collectively the most dangerous drug, when both harm to self and others were taken into account. We have some way to go as a society, until we can really look at drugs in an adult way, based upon evidence and risk, rather than entrenched positions.
The Army's attitude to those who fail a drugs test should be based upon evidence and balance of risk, including risks from low recruitment and retention.