By legal definition, the ‘use’ of Cannabis is not illegal but any other form of dealing with the substance is; especially production, possession, taking it across national borders and passing it on to others. So in practice, only smoking in an unconscious condition would not be illegal. The police have to report offences to the public prosecutor. Then the case may be put aside under probation or you are „invited“ to see the public health medical officer who then decides if you need any kind of therapy. If you do not agree to undergo the suggested therapy you will be formally convicted by court to pay a fine. The Administrative Court has ruled 1999 und dozens of times since then that consuming cannabis from time to time does not endanger your driving license, unless you drive in an intoxicated condition.