Drunk in charge of camper van

kbell

If you’re locked and decided to spend the night in your car, if you are in Possession of the keys and a garda came calling, you can be done for being in charge of your vehicle. Can the same apply to your camper van if you’re sleeping or indeed drinking in the back if it.
If it’s on private land would it be ok as opposite to a lay by on side of the road.

Victor

kbell wrote: »

If it’s on private land would it be ok as opposite to a lay by on side of the road.

That depends, does the general public have access to that place, with or without a fee? If they do, drink driving laws apply (speed limits don't).

kirving

I've heard of people leaving the key out outside of the vehicle so that they couldn't be accused of trying to drive.

Claw Hammer

kbell wrote: »

If it’s on private land would it be ok as opposite to a lay by on side of the road.

Private land may well be "a public place" for the purposes of the Road Traffic Act. A classic example is the car park of a supermarket.
"A public place” means any street, road or other place to which the public have access with vehicles whether as of right or by permission and whether subject to or free of charge;

Leaving keys outside the vehicle is of no avail. Once the intention to drive the vehicle at some point in the future as present that is sufficient.

Montage of Feck

So basically the under law if you are drunk and in a motor vehicle you can be done as it will obviously be driven in the future.

Claw Hammer

Montage of Feck wrote: »

So basically the under law if you are in a motor vehicle you can be done as it will obviously be driven in the future.

If in a public place, yes.

monseiur

Claw Hammer wrote: »

If in a public place, yes.

No so. If the vehicle is parked up in a safe place, not causing obstruction etc.
the drunk driver may be in the passanger seat or in the back of the vehicle and cannot not be done for drink driving - whether it's a camper van or not, the type of mpv has no bearing on the issue.
Unless of course '' In the opinion of a Garda'' the said drunk driver deliberately parked up and jumped in the back to avoid detection.

Claw Hammer

monseiur wrote: »

No so. If the vehicle is parked up in a safe place, not causing obstruction etc.
the drunk driver may be in the passanger seat or in the back of the vehicle and cannot not be done for drink driving - whether it's a camper van or not, the type of mpv has no bearing on the issue.
Unless of course '' In the opinion of a Garda'' the said drunk driver deliberately parked up and jumped in the back to avoid detection.

Rubbish. If the drunk driver intends to drive away from the safe place not causing obstruction he is drunk in charge of a vehicle in a public place. What seat he is in is irrelevant as is whether he is in the front or the back.

timmyntc

Claw Hammer wrote: »

Rubbish. If the drunk driver intends to drive away from the safe place not causing obstruction he is drunk in charge of a vehicle in a public place. What seat he is in is irrelevant as is whether he is in the front or the back.

And how do you measure intent to drive?
its not exactly a quantifiable thing, someones future intent. So from that POV, being in the back seat makes you much less likely to intend to drive than being in the front.

Claw Hammer

timmyntc wrote: »

And how do you measure intent to drive?
its not exactly a quantifiable thing, someones future intent. So from that POV, being in the back seat makes you much less likely to intend to drive than being in the front.

It is a matter for the court to review the evidence. Does the person intend to vacate the vehicle, walk away and never drive it from the scene?

https://www.courts.ie/acc/alfresco/78ad013a-05da-42c6-b5b8-84815e51f60b/2001_IESC_97_1.pdf/pdf#view=fitH

Del2005

monseiur wrote: »

No so. If the vehicle is parked up in a safe place, not causing obstruction etc.
the drunk driver may be in the passanger seat or in the back of the vehicle and cannot not be done for drink driving - whether it's a camper van or not, the type of mpv has no bearing on the issue.
Unless of course '' In the opinion of a Garda'' the said drunk driver deliberately parked up and jumped in the back to avoid detection.

Driving Under the Influence (DUI) and being Drunk in Charge (DiC) are 2 separate offences. You can't be done for DUI unless the Garda has seen you driving, you can be done for DiC if you are in a public place.

timmyntc

Claw Hammer wrote: »

It is a matter for the court to review the evidence. Does the person intend to vacate the vehicle, walk away and never drive it from the scene?

https://www.courts.ie/acc/alfresco/78ad013a-05da-42c6-b5b8-84815e51f60b/2001_IESC_97_1.pdf/pdf#view=fitH

That is news to me.

The relevant provisions of Section 50
creates an inextricable link between being in charge and the intention to drive. In the example given the sole purpose is to
retrieve something from the car with the intention of leaving the car and returning to his house. There could not be said to be
present in his mind an intention to drive while in charge of the car. There is an intent to relinquish or abandon his charge
without driving. The link between being in charge of a vehicle and the intent to drive must mean that in the circumstances in
which the Defendant is found to be in charge he has an intention, at some point, while in charge, to drive the motor vehicle. It
is that intention which does not have to be immediate or an intention to do so within a particular time-frame.

So unless there is a clear intention to leave the car (no longer in-charge of said vehicle) before driving it next you are liable, even if you wouldnt be driving for 8hrs+ and by the time you wake up would be totally sober.
Seems like quite a harsh interpretation of the law tbh

monseiur

Claw Hammer wrote: »

It is a matter for the court to review the evidence. Does the person intend to vacate the vehicle, walk away and never drive it from the scene?

https://www.courts.ie/acc/alfresco/78ad013a-05da-42c6-b5b8-84815e51f60b/2001_IESC_97_1.pdf/pdf#view=fitH

Bad cases make bad laws
Edward Byrne in this particular court case was fast asleep in the drivers seat with the key in the ignition. Also the car was parked on the hard shoulder which is more for emergencies that overnighting.
Had he parked up in a ''safe place'', removed keys form ingitioin, dozed off in the passenger seat or in the back things would be very different.

John_Rambo

If you've a bit of cop and you know where to park (where you won't be asked to move) you will not be done for drunk driving if you're asleep in a bunk in a Campervan after a few drinks.

Just don't leave the keys in the ignition, don't start the engine to charge batteries and don't sit in the drivers seat unless it's captain seat and reversed.

RobbieMD

Del2005 wrote: »

Driving Under the Influence (DUI) and being Drunk in Charge (DiC) are 2 separate offences. You can't be done for DUI unless the Garda has seen you driving, you can be done for DiC if you are in a public place.

The garda doesn’t necessarily have to see you driving to prosecute for drunken driving. And a judge if satisfied can give an alternative verdict and convict for drunken driving even though the person may be charged with drunk in charge.

Peregrinus

RobbieMD wrote: »

The garda doesn’t necessarily have to see you driving to prosecute for drunken driving. And a judge if satisfied can give an alternative verdict and convict for drunken driving even though the person may be charged with drunk in charge.

Yes he can, but in order for him to do that there would have to be evidence of the defendant driving or attempting to drive. And the usual reason for brining the drunk-in-charge prosecution is that the guard doesn't have evidence of driving or attempt. So cases in which the judge would end up convicting for that are rare, and usually arise only because the defendant himself gets into the box and supplies the necessary evidence.

monseiur

John_Rambo wrote: »

If you've a bit of cop and you know where to park (where you won't be asked to move) you will not be done for drunk driving if you're asleep in a bunk in a Campervan after a few drinks.

Just don't leave the keys in the ignition, don't start the engine to charge batteries and don't sit in the drivers seat unless it's captain seat and reversed.

Yes John, that about sums it up. Unfortunately when too much drink is consumed a bit of cop on is the first casualty and drunk drivers park on hard shoulders etc. with lights on, key in ignition etc. attracting the attention of the cops.
Even without drink taken common sense is not too common !

Claw Hammer

timmyntc wrote: »

That is news to me.



So unless there is a clear intention to leave the car (no longer in-charge of said vehicle) before driving it next you are liable, even if you wouldnt be driving for 8hrs+ and by the time you wake up would be totally sober.
Seems like quite a harsh interpretation of the law tbh

That is what the supreme Court says and all other courts are bound by it. People who rely on this back seat, keys under a hedge bull**** may well end up with a fine and a ban. It would be cheaper to stay in a 5* hotel.

Claw Hammer

monseiur wrote: »

Bad cases make bad laws
Edward Byrne in this particular court case was fast asleep in the drivers seat with the key in the ignition. Also the car was parked on the hard shoulder which is more for emergencies that overnighting.
Had he parked up in a ''safe place'', removed keys form ingitioin, dozed off in the passenger seat or in the back things would be very different.

The principle is the same. What element of the judgement say there would have been a different outcome if he was in the back seat with keys removed from the ignition? The lower courts are now bound by it. Thank Edward Byrne.

timmyntc

Claw Hammer wrote: »

The principle is the same. What element of the judgement say there would have been a different outcome if he was in the back seat with keys removed from the ignition? The lower courts are now bound by it. Thank Edward Byrne.

That case is messy, firstly because of his own admission that he fell asleep at the wheel unconsciously. It was based partly on that, that they decided his future intent was to drive.

If he had fallen asleep in the backseat it could be said he clearly had intent to sleep it off and not drive. The law is not well defined on the length of intent - as the judge said in that ruling, intent is grand if its 3, 6, 9 hours ahead, but at some stage you have to say its ludicrous to say the driver had intent to drive that far ahead in time.

Given a different test case it could easily have been seen in a different way, where no keys in ignition but still having the keys and being in a non-driving position (i.e. back-seat) would not demonstrate intent to drive and would be fine.

CoBo55

So the question still remains unanswered, can you go somewhere in a camper, park in a car park, get a few beers and head for bed without fear of being collared by the boys in blue? I know many that have and still are doing this, are they chancing their respective arms?

elperello

kbell wrote: »

If you’re locked and decided to spend the night in your car, if you are in Possession of the keys and a garda came calling, you can be done for being in charge of your vehicle. Can the same apply to your camper van if you’re sleeping or indeed drinking in the back if it.
If it’s on private land would it be ok as opposite to a lay by on side of the road.

If you are in bed in your pj's in the back of the campervan on private land the chance of facing charges is nil.

If you are pulled in at the side of road fully dressed in the back of the campervan necking cans there is a strong chance of facing charges.

In between those two scenarios there are various other circumstances that may result in you facing charges.

BattleCorp

If you are full to the neck and asleep in the back of a camper van, and the van is parked somewhere safe, would the Gardai have the powers to wake you up and breathalise you? Do they not need to form an opinion that you have been drinking before they can breathalise you under those circumstances?

I understand it would be a different scenario if the Gardai see you stagger towards the camper van as it would be easy to form an opinion that you have been drinking.

John_Rambo

monseiur wrote: »

Yes John, that about sums it up. Unfortunately when too much drink is consumed a bit of cop on is the first casualty and drunk drivers park on hard shoulders etc. with lights on, key in ignition etc. attracting the attention of the cops.
Even without drink taken common sense is not too common !

Has this happened to someone in a Campervan in Ireland?

Claw Hammer

timmyntc wrote: »

That case is messy, firstly because of his own admission that he fell asleep at the wheel unconsciously. It was based partly on that, that they decided his future intent was to drive.

If he had fallen asleep in the backseat it could be said he clearly had intent to sleep it off and not drive. The law is not well defined on the length of intent - as the judge said in that ruling, intent is grand if its 3, 6, 9 hours ahead, but at some stage you have to say its ludicrous to say the driver had intent to drive that far ahead in time.

Given a different test case it could easily have been seen in a different way, where no keys in ignition but still having the keys and being in a non-driving position (i.e. back-seat) would not demonstrate intent to drive and would be fine.

It may have been a messy set of facts but it sets out the law. It would take another case to refine things as to how far in the future the intent to drive can be deferred. In any event nothing turns on what seat the person is in or whether he is asleep or awake nor where the keys are. The sole occupant of a vehicle is in control of it and their only defence is that they do not intend to drive the vehicle in the future.
If you are over the drink drive limit and sleep in a vehicle in a public place you are at risk of a prosecution with no certainty of a defence.

Claw Hammer

CoBo55 wrote: »

So the question still remains unanswered, can you go somewhere in a camper, park in a car park, get a few beers and head for bed without fear of being collared by the boys in blue? I know many that have and still are doing this, are they chancing their respective arms?

NO.

krissovo

Common sense prevails, in 20 years of regularly sleeping in campervans 50% wild and partial to a glass or 3 of wine its never been a problem. If I am drinking the keys are always in a lock box at the rear and the van is clearly in a parked for night state i.e. looking like a mess and lived in with stuff spread out and washing up in the sink.

In that time I have 4 encounters, 2 at the beach and one at a wedding where I stayed in the car park and was in a really bad state. All were fine once they seen I was well settled. I had a Garda knock on my van in Garrettstown a few weeks ago and I answered the door holding a glass of wine, I ended up making him a cup of coffee.

GerardKeating

Del2005 wrote: »

Driving Under the Influence (DUI) and being Drunk in Charge (DiC) are 2 separate offences. You can't be done for DUI unless the Garda has seen you driving, you can be done for DiC if you are in a public place.

If Four or Five people are drunk in the back of a CamperVan, could all of them be charged with "Drunk in Charge (DiC)" or how would the Garda decide which to charge ?

Robbo

Claw Hammer wrote: »

It may have been a messy set of facts but it sets out the law. It would take another case to refine things as to how far in the future the intent to drive can be deferred. In any event nothing turns on what seat the person is in or whether he is asleep or awake nor where the keys are. The sole occupant of a vehicle is in control of it and their only defence is that they do not intend to drive the vehicle in the future.
If you are over the drink drive limit and sleep in a vehicle in a public place you are at risk of a prosecution with no certainty of a defence.

Claw Hammer wrote: »

NO.

Claw Hammer wrote: »

The principle is the same. What element of the judgement say there would have been a different outcome if he was in the back seat with keys removed from the ignition? The lower courts are now bound by it. Thank Edward Byrne.

No doubt that Byrne was an odd set of facts but I'd point out that Byrne referred to the English decision on DPP v. Watkins [1989] RTR 324. Here, Taylor LJ noted that the circumstances in which a person may be "in charge" can "vary infinitely" and that there isn't a single test that can cover the factual faviance. In Staunton's book, after introducing Byrne, he states that whether a person is "in charge" is still very much a matter for the trial judge to determine on evidence tendered.

I don't think that any prosecuting Garda giving evidence of how they knocked on the side door of a campervan to be confronted by the pyjama-clad owner with a glass of booze in one hand and Coronation Street on the telly would get too far in front of a DJ.

John_Rambo wrote: »

Has this happened to someone in a Campervan in Ireland?

I can't find a single judgment of the Superior Courts which concerns a campervan and drink driving.

Peregrinus

Apart from having drink taken, there are two main elements to this offence; being in charge of a motor vehicle (which is usually established by being in possession or control of the keys) and having the intent to drive or attempt to drive. Once the other elements are established there's a presumption that you have the intent; the onus is on you to produce or point to evidence that you didn't. Being tucked up in bed for the night, or otherwise clearly settled in for the long haul, would do the trick; it doesn't absolutely prevent you from driving, since you could get out of bed at any time, but it does point to your not intending to drive, which is what you need.

Claw Hammer

Peregrinus wrote: »

Apart from having drink taken, there are two main elements to this offence; being in charge of a motor vehicle (which is usually established by being in possession or control of the keys) and having the intent to drive or attempt to drive. Once the other elements are established there's a presumption that you have the intent; the onus is on you to produce or point to evidence that you didn't. Being tucked up in bed for the night, or otherwise clearly settled in for the long haul, would do the trick; it doesn't absolutely prevent you from driving, since you could get out of bed at any time, but it does point to your not intending to drive, which is what you need.

The trouble with that is that Byrne says that future intent to drive is sufficient. No assistance is given as to when it may be taken as to when the intent to drive is. As Byrne shows the fact of being asleep itself is not enough.
So far no poster has found any case to show definitively that a person can be in a vehicle in a public place in possession or control of the keys and escape sanction.

Peregrinus

Nitpick: not a future intent to drive; a present intent to drive at a future time.

But not at any future time. The mere possesion or, indeed, ownership of a car suggests an intent to drive at some point. But good luck getting someone convicted on the basis that (a) he's drunk and (b) he owns a car. The intention to drive at some future time must be an intention to drive at a time close enough that the defendant's present state of intoxication is a relevant consideration.

Nobody's found a case in which the evidence suggested an intent to drive a future time when sober, and a conviction ensued. And that, I think, points to the boundary of legally safe behaviour.

Claw Hammer

Peregrinus wrote: »

Nitpick: not a future intent to drive; a present intent to drive at a future time.

But not at any future time. The mere possesion or, indeed, ownership of a car suggests an intent to drive at some point. But good luck getting someone convicted on the basis that (a) he's drunk and (b) he owns a car. The intention to drive at some future time must be an intention to drive at a time close enough that the defendant's present state of intoxication is a relevant consideration.

Nobody's found a case in which the evidence suggested an intent to drive a future time when sober, and a conviction ensued. And that, I think, points to the boundary of legally safe behaviour.

That is the problem, nobody has argued that an intent to drive when sober is sufficient. The Byrne case specifically states that an intention to drive at some point in the future is sufficient. You state as a matter of opinion is that if evidence is offered of an intention to drive when sober an acquittal would result. That means someone has to take their chances and given that Byrne is a Supreme Court decision, it would be highly a District Court judge would defy it. Byrne is open ended as far as the future intent to drive is concerned.
It would be cheaper to stay in a 5* hotel that take ones chances on an argument in the District Court. A thick garda followed by a thick judge and a conviction would ensue.

Peregrinus

And yet, despite this offence or a similar one having been on the statute books for many decades, this has never happened. Gosh! I wonder why?

Byrne doesn't say that a present intent to drive in the future ever, at any time, is sufficient to constitute the offence; it just says that no particular timeframe is specified. The court is quite clear about this; "It would not be a defence for a defendant to admit that he was in charge of a motor vehicle . . . but did not intent to drive for 3½ hours, 6 hours or as the case may be". And this makes perfect sense since, from a public policy point of view, the important question is not in what time frame exactly will you drive, but whether you will be sober when you drive, a question only tangentially related to the matter of timeframe.

In Byrne's case matters were pretty clear-cut. The defendant was sitting in the driver's seat, with the keys in the ignition and the lights turned out, stopped at a place at which he had no reason to remain. The onus was on him to adduce evidence rebutting the presumption of an intent to drive. His argument on this point didn't focus at all on how long it would be before he drove but rather that, being asleep, he couldn't be said to have had any intention to do anything — an argument that failed, because the court found that his actions before falling asleep (getting into the car, putting the key in the ignition, turning on the lights) evidenced an intention to drive which wasn't lost on falling asleep. There was no argument that the evidence pointed to an intention to drive when sobered up because, frankly, there was no evidence pointing to such an intention. So Byrne is not an authority for the proposition that an intention to drive when sober is sufficient to constitute the offence; the point was never argued.

Claw Hammer

Peregrinus wrote: »

And yet, despite this offence or a similar one having been on the statute books for many decades, this has never happened. Gosh! I wonder why?

Byrne doesn't say that a present intent to drive in the future ever, at any time, is sufficient to constitute the offence; it just says that no particular timeframe is specified. The court is quite clear about this; "It would not be a defence for a defendant to admit that he was in charge of a motor vehicle . . . but did not intent to drive for 3½ hours, 6 hours or as the case may be". And this makes perfect sense since, from a public policy point of view, the important question is not in what time frame exactly will you drive, but whether you will be sober when you drive, a question only tangentially related to the matter of timeframe.

In Byrne's case matters were pretty clear-cut. The defendant was sitting in the driver's seat, with the keys in the ignition and the lights turned out, stopped at a place at which he had no reason to remain. The onus was on him to adduce evidence rebutting the presumption of an intent to drive. His argument on this point didn't focus at all on how long it would be before he drove but rather that, being asleep, he couldn't be said to have had any intention to do anything — an argument that failed, because the court found that his actions before falling asleep (getting into the car, putting the key in the ignition, turning on the lights) evidenced an intention to drive which wasn't lost on falling asleep. There was no argument that the evidence pointed to an intention to drive when sobered up because, frankly, there was no evidence pointing to such an intention. So Byrne is not an authority for the proposition that an intention to drive when sober is sufficient to constitute the offence; the point was never argued.

the point was never argued so the situation remains open. If defending someone charged all of that would be argued. What the o/p is seeking is prescriptive as in what can I do to ensure I am not charged or convicted. Byrne does not close off the intention to drive when sober. A person who parks up or enters a vehicle while over the limit, has control; of the keys clearly intends to drive at some point in the future. The may intend to drive only when sober but the offence is made out if the intend to drive at all. Byrne does not definitively close that off.
A person who pitches a tent in a public place and sleeps in in beside a vehicle which is also in a public place and of hich the person has control of the keys may be guilty of the offence.
Likewise a person who is parked on the public road outside their house could be charged if they left the house to retrieve something from the vehicle.
The fact that there hasn't been a reported case is not unusual. DUI and DIC are dealt with in the District Court. Most guards use their discretion. only a tiny fraction of cases reach the High Court or the appeal courts.

athlone573

Claw Hammer wrote: »

Likewise a person who is parked on the public road outside their house could be charged if they left the house to retrieve something from the vehicle.
.

Doesn't the top judge cover that situation in their judgement, as not an offence?

Peregrinus

Claw Hammer wrote: »

. . . The fact that there hasn't been a reported case is not unusual. DUI and DIC are dealt with in the District Court. Most guards use their discretion. only a tiny fraction of cases reach the High Court or the appeal courts.

Yeah, but the likely reason why we know of no reported cases is not that such convictions occur but are not appealed; it's that such convictions don't occur because prosecutions are not mounted in these circumstances.

I can hear you saying that the costs of appealing are such that there may be many convictions of this kind and we'd never hear about them because no one would want to bear the costs of the appeal. But one of the things that struck me when I was formally studying the law of evidence, back in the late middle ages, was the astonishing proportion of superior court precedents that had been established in drink driving cases of one kind or another. It may be expensive to appeal a drink-driving conviction on a technical point (and evidence points are always technical) but there seemed to be no shortage of drink drivers willing to bear the expense. I don't know whether this is due to the very considerable economic impact, for many people, of a driving disqualification or to a psychological unwillingness on the part of many drivers ever to admit, even to themselves, that they might possibly have done something wrong, or a combination of the two, but there it is. If there is ever a District Court conviction that's going to be appealed on the question of whether there was sufficient evidence to prove X or Y or Z point, odds are it'll be a drink-driving conviction. And therefore, while nothing is proven, the theory that these convictions occur but are never appealed does not seem to me to be a very likely one.

Claw Hammer

Peregrinus wrote: »

Yeah, but the likely reason why we know of no reported cases is not that such convictions occur but are not appealed; it's that such convictions don't occur because prosecutions are not mounted in these circumstances.

I can hear you saying that the costs of appealing are such that there may be many convictions of this kind and we'd never hear about them because no one would want to bear the costs of the appeal. But one of the things that struck me when I was formally studying the law of evidence, back in the late middle age, was the astonishing proportion of superior court precedents that had been established in drink driving cases of one kind or another. It may be expensive to appeal a drink-driving conviction on a technical point (and evidence points are always technical) but there seemed to be no shortage of drink drivers willing to bear the expense. I don't know whether this is due to the very considerable economic impact, for many people, of a driving disqualification or to a psychological unwillingness on the part of many drivers ever to admit, even to themselves, that they might possibly have done something wrong, or a combination of the two, but there it is. If there is ever a District Court conviction that's going to be appealed on the question of whether there was sufficient evidence to prove X or Y or Z point, odds are it'll be a drink-driving conviction. And therefore, while nothing is proven, the theory that these convictions occur but are never appealed does not seem to me to be a very likely one.

Drink driving is heavily litigated but even so the number of cases going to the Superior Courts is a tiny fraction of the overall number. Many defendants plead guilty on day 1. There are about 1000 drink driving arrests a month. Only a handful result in a hearing before the Superior courts.

Peregrinus

Claw Hammer wrote: »

Drink driving is heavily litigated but even so the number of cases going to the Superior Courts is a tiny fraction of the overall number. Many defendants plead guilty on day 1. There are about 1000 drink driving arrests a month. Only a handful result in a hearing before the Superior courts.

I know. But that's because they are mostly very cut-and-dried. That was the whole point of the breathalyzer system - to produce an offence that it would be all but impossible to appeal, given the very strong propensity of drink-driving defendants to appeal.

But if somebody was convicted on of evidence pointing to an intention to drive only when sober - yeah, high chance of an appeal there, given the fact that the propriety of such a conviction has never been tested. There are incentives there - good arguable case on the one hand, high economic costs if the conviction is allowed to stand on the other - that seem almost precisely designed to encourage the drink-driver's instinct to appeal.

Claw Hammer

Peregrinus wrote: »

I know. But that's because they are mostly very cut-and-dried. That was the whole point of the breathalyzer system - to produce an offence that it would be all but impossible to appeal, given the very strong propensity of drink-driving defendants to appeal.

But if somebody was convicted on of evidence pointing to an intention to drive only when sober - yeah, high chance of an appeal there, given the fact that the propriety of such a conviction has never been tested. There are incentives there - good arguable case on the one hand, high economic costs if the conviction is allowed to stand on the other - that seem almost precisely designed to encourage the drink-driver's instinct to appeal.

If the drink driver can afford it. In most cases guards will not charge in a bona fide situation. If someone is asleep in the back of a van or car, the guard has no real basis for waking them up in order to smell their breath. Likewise most judges would be inclined to some sympathy for the individual.
The fact that there is no case doesn't mean that guards are ignoring possible cases. There is a fetish or trying to get drink driving prosecutions. One assistant commissioner now retired wanted returns every month for every district showing the statistics for drink driving checkpoints, detections, arrests, prosecutions and convictions. It led to the fake breathalyser statistics. It was made known that career opportunities would be influenced by good statistics.
The o/p wanted to know if there was a formula he could use which would guarantee no prosecution.
There isn't one which is guaranteed. Nobody wants to be the test case. It is better to park on private land or not drink.

Day Lewin

This question comes up time after time on the various camper-van groups that I'm a member of (Lots and lots!)

Short answer; may be technically illegal, theoretically you could be arrested. After all, you are apparently "in charge of" a vehicle.

Real-life answer: Police don't really bother overnight campers unless there is some other reason - if you're causing a nuisance, or you resemble a known criminal - or they have some reason for being "out to get you".

But generally speaking, it's all fine.

Spent many a night at a roadside parking space in the old van, gin-and-tonic and a glass of wine - nary a word being said by anyone.

There was one slightly hairy moment when overnighting in a layby at a picnic spot in Northern Ireland, and an RUC car slowed to a crawl seeing an Irish-reg van - but when they saw the net curtains at my windows they pottered off again!