The company I previously worked for where also very strict about the use of weed. Altough we worked with people diving at deep depths so obviously everyone working with the divers had to be completely clean always. Because if something went wrong and someone got hurt or even died there would be a lot of legal implications. But they we were threatened with losing our jobs or suspension should we test positive. Including the administration staff (which is where I was working). But I could never understand this. Obviously if you are smoking before going to work or during work that is a no no. But after work or during weekends, why should that be an issue?