Tourists can have up to 5g of weed on them for personal use the same as locals can with the exception of smoking in the red light district. You can still carry it there just not smoke.
Other drugs are legal like magic truffles you can get from a shop there are no restrictions for tourists, whatever a local can get so can a tourist. It was either more than 5G on her personally or something else that is genuinely illegal.
You can get an attorney when you get to police station, they can put you in a van or whatever to arrest you if you have been caught with illegal possession.