I'd report him to work. I reported someone driving their sign-written work van that was following me to work one day. They spent the entire journey talking on their phone, texting and taking selfies. The company was very grateful to have been told.
Smoking excessive amounts of weed while in a company vehicle is not only illegal from the smoking front, but there's also a chance if he's doing it that much that he's over the drug driving limit and could lose his licence completely. Extract from a solicitors website:
"England and Wales have a zero-tolerance approach to drug driving. This means you cannot operate a vehicle in a public place while you have illegal drugs in your system. This applies, even if you do not feel impaired.
When it comes to cannabis, it could be argued that it is not strictly a zero-tolerance approach, as drivers are actually allowed two micrograms of THC per litre of blood. However, this is really a very small amount. In fact, merely being exposed to cannabis smoke could push you over the legal limit.
If you are caught driving with more than two micrograms of THC per litre of blood, you could be charged with drug driving. More specifically, you will be charged with operating a vehicle while unfit through drugs. This carries a range of potential penalties, including:
- A 12-month driving ban
- A fine
- A six-month prison sentence
- An endorsement on your licence for up to 11 years"
Unfortunately if he loses his job it means he's likely to spend more time at home smoking weed, so it might not actually resolve your issue!