well first of all in the laws of amsterdam (holland): Under Dutch drug law, coffeeshops are allowed to sell a maximum of five grams of cannabis per person to their customers, providing said customers can present identification to show that they are over 18 years old. This can be quite strict in many coffeeshops, so be prepared to prove your age, even if you haven't been carded for years back home. Other restrictions apply under Amsterdam's drug laws, such as the fact that it is not allowed to sell alcohol and cannabis products on the same premises. Since 2008 the introduction of the tobacco ban has made it illegal to smoke this dangerous substance in anyone's workplace. Pure cannabis joints may still be smoked as normal, as may bongs, pipes and joints made with the special 'herbal smoking mixtures' provided by some coffeeshops. Many coffeeshops also have a sealed 'smoking area' in order to allow customers to smoke joints containing tobacco.
No coffeeshops permit the use of hard drugs and you will find yourself ejected quite quickly should you try to test this.