@randomvim My parents had a similiar approach and I understand that this can work with some children but for me it was not just weed. When I was 14-years old the police caught a friend smoking weed and he got it from my girlfriend at that time who was 17-years old. My parents found out because I got a letter from the police. Nothing really happened but my parents were pretty angry and did not want me to have legal issues. Which I did not have in the end.
My parents tested me on weed regularly but I did not smoke anything. But I started to search for other options. Started to do stuff like magic truffles and salvia because they were easy available for minors. I later started taking alcohol half a year before I turned 16 and had problems at school. Beer is available at the age of 16 in my country. My parents enabled it. I started having bad grades at school and though about getting a job instead of education. But I did not want people to think that I was dumb and tried to better my grades. I stopped drinking and really improved a lot at school. I still wanted to take drugs and found kratom. It's a plant from Thailand that acts similiar to stuff like codeine or morphine but is not lethal and less habit forming, bla bla bla, that's not the point actually. Because I knew that kratom acts like other opioids I got interested in abusing medicine. We had around five bottles of codeine at home and I took them over time. My mother clearly knew that but we did not talk about that. (She even got me some codeine when I told her I was ill) I was in therapy at that time because of OCD maybe she thought I was self medicating or something. I started going on raves when I was 16. i already tried ecstasy at a friends house. Me and a friend bought ecstasy that was way stronger than we thought and went to my parents house. My brother saw us and told me that our parents should not see us like that. We went quietly in my room but we were talking loudly when we finally arrived. Suddenly my mother went in my room and it was obvious that we have taken drugs. She asked me once. I said "no" and the conversation was over. After that experience I knew that I could do what I want. Over the next few years I started experimenting a lot with different drugs. The same year I took speed and cocaine. With 17 I took crystal, oxycodon and ketamine and with 18 I took heroin, PCP and fentanyl.
My parents told me that I can do what I want as long as my grades are good and my grades were great but I still developed a very bad habit with polytoxic drug use. I took everything I could get my hands on. Every medicine, plant and chemical but my grades were good. I nearly killed myself more than once. I often passed out and my parents saw it. I urinated myself twics while I passed out. I got manic. I got anxious. I got a 10 minute long seizure on tramadol and got stab wounds while shaking unconsciously but my grades were great.
I mean I love my parents but the way they treated my clearly destructive drug habit was not healthy. I think my mother was pretty codependent. Me and my brother both used drugs but she always seemed to but it in a box in her mind and never ever look at it again. And my father wanted to be more accepting but it did not work out that good. Both don't know about stuff like heroin and I think they would have acted different but the drug problems in my family were visible. Also my mum found xanax while I was unconscious so I think she knew that I was taking stuff that can be pretty addictive.
I don't say parents should be authoritarian about drugs. I think talking about drug use is important and having rules is also important. A 13-year old person should not smoke weed. Maybe talk with him about the fact that you are not against weed but against a 13-year old smoking weed. And look for other signs of drug use. At best tell your child that you can talk about such stuff. There are a lot of other things people take that is not weed. Stuff like whipped cream capsules or specific plants. Depends on were you life. Just show your kid that you will not be mad and that you just want to be a helpful parent.
Also when your kid is drug seeking maybe consider therapy. A lot of people self medicate themselfs. I now know that I have BPD which is associated with drug use.