captplaystation,
Holland is a tolerant place, but the authorities are also big on personal responsibility. Especially for people with jobs that bear responsibility for other people's lives. So yes, cannabis is fine and you won't be prosecuted if you possess and use it in minor quantities and don't put other people at risk, for example by driving a car or flying an airplane while under it's influence. Same goes for alcohol. Oh, by the way: cannabis is technically not legal in Holland, and certainly not for pilots.
Being caught over the limit as a pilot is a disgrace and reflects badly on all of us, I'm with the dutch police on this one. Giving out to the dutch authorities is not on in this case.
Paulsen:
If he was in the flight deck conducting a line check or as a safety pilot he was working and on the crew list. It is legal in Holland for the police to seize a pilot's or driver's licence after an offence. The public prosecutor will subsequently decide if you get it back.