The drug driving laws that were bought into power in 2015 with new roadside tests have done what they intended to do. Not stopping people from driving while high on coke or THC, that was never the aim. The aim was to make the law so ambiguous that you couldn’t realistically smoke cannabis regularly and not get banned from driving on the off chance that you get pulled over.
So, they’ve done what they aimed to - I’ve quit smoking cannabis because I drive every day. That was the aim all along. The government realises that you’re never going to catch people smoking cannabis, and police forces have better things to do with their time, so they’ve just made it as awkward as possible.
The limit for drug driving is 2mg per litre of blood, which is not a lot. It’s almost impossible to tell when you’re under the limit. You could be over the limit three days after you last smoked if you’re a regular smoker. There is an automatic driving ban if you’re over the limit too. Even if a judge wanted to help you out, if you had a good reason to continue driving, for example if your job depended on it, like they do with driving under the influence of alcohol, they couldn’t do anything, the ban is automatic.
If you have a steady job and a driving license that you need, you can’t safely smoke cannabis in the UK anymore, there’s just too much risk. Which is exactly what the government wanted all along. It wasn’t about safety, it was about sending a message.