heres my solution to the situation in the UK. If you are EVER planning on sleeping it off in the car, get a breathalyzer locking cabinet for your keys.
this way you can prove unambiguously that you are unable to operate the vehicle even if you wake up and are over the limit... there.. problem solved. Now lets get back on track about the right to read all communications.
even if they backdoor all chat messages, you can still use your own encryption within that channel. Everyone can do this using free open source software and even custom keyboards in android (I don't use iPhone so I don't know about them).
What happened to good old fashioned spycraft following people around and occasionally plutonium pelleting someone in the leg with an umbrella.
What is the legal definition of being in charge?
There is no legal definition for the term "in charge" so each case will depend on its exact circumstances and facts. Generally, a Defendant is "in charge" if he was the owner/in possession of the vehicle or had recently driven it. He is not in charge if it is being driven by another person or is "a great distance" from the vehicle.
Matters are more complicated where a person is sitting in the vehicle or "otherwise involved with it". In charge can include attempting to gain entry to the vehicle and failing, having keys to the vehicle, having intention to take control of the vehicle or even "being near the vehicle".
This opens a WHOLE can of worms for me as I do live in the UK.. and I regularly get drunk and sleep in my campervan. According to this particular interpretation, all campervan owners who get drunk and sleep in the van can be arrested. Im thinking that due to there is no legal definition of "in charge" that this could definitely be argued in court.
I think it is all about presentation (and how you speak to the police)
While you can reasonably be deemed "in charge" of your camper van, if you're seen climbing into the living area with the clear intention of bedding down for the night, or are knocked awake by the police and then breathalysed, you would have a very good argument that there was no likelihood of your driving the vehicle, and therefore you would have a defence against the charge.
If, on the other hand, you climbed into the drivers seat and started the engine so you could turn on the heaters and put the radio on for a bit while you had your evening cocoa, you'd have a rather more difficult hill to climb.
If you make a habit of sleeping somewhere other than a recognised camp site, it would probably be worth your while keeping a couple of those £2 disposable breathalysers from Halfords in the glove box. Not only will it prevent you from accidentally driving while still over the limit the next day, but if you are challenged by the police while you're still drunk, it allows you to demonstrate that you have the means on hand to ensure that you won't be driving before you're fit to do so.
In the same way reading communications can be perfectly legal and is often helpful in establishing conspiracy cases. Accepting that Governments can legally intercept communications with some form of due process shouldn't be viewed as going after "pre-crime". It has always been the case before now that legal interception powers also enable illegal Government (or indeed non-state) snooping, that should be dealt with by robust interventions by an independent judiciary.
* Road Traffic Law is one of the relatively few criminal areas that is UK wide