Random testing is voluntary and for good reason
The police do not have the power to randomly breath test drivers, however, under the RTA they do have the power to stop practically anyone they like for a whole variety of reasons.
Once they have stopped someone, they can ask for a breath test if they have reason to suspect that the driver has been drinking.
Again, this does not need to be complicated. If you were seen to weave a little, or fail to indicate somewhere, or any one of a thousand other minor 'reasons' will do.
If you fail to co-operate you could be arrested for failing to provide a specimen of breath, the punishment for which is as bad, or worse, than failing a breath test.
So, the short answer is 'no' they cannot do random tests, but it doesn't take much effort on their part to make it totally legitimate.
Whats more, I am in full agreement with the posters above, that I am more than happy to know that practically anyone can be stopped and breathalysed at practically any time. I only wish that they would do it more often, and have a simple means for testing for drugged drivers as well (I am convinced that that is if anything a worse problem than alcohol!). However, whilst we have 'powers that be' who think that cameras can keep us safe that won't change!
Sorry - necro thread ressurection
But this is VERY annoying.
They're not allowed to randomly test you, and for very good reason.
Because it's breaking the principal of reasonable suspicion.
The police have licence to test you if they have reasonable suspicion - fair enough.
But if they don't have reasonable suspicion then they're detaining you without just cause. It could be called one of many things, a lawyer would know, but it's false arrest/imprisonment or something in that vein and is just the same as stopping black people because they are black.
We have police to act on our behalf, not theirs. We elect parliamentary representatives, who decide on the law of the land - they're OUR laws and we employ the police to 'police' them, not break them.
So they have a legal licence to detain you if they have just cause, for a breath test. If they do not have just cause then they are breaking the law.
And it's an important law - being detained is very serious and supporting 'random' tests is a slippery slope to a police state - where they can just choose who to hassle at random.
We have already lost a VERY important facet of legal protection - if your car is clocked by a 'safety' camera then the OWNER is obliged to tell the authorities who was driving it at the time. The actual guilty party is not identified. That goes against the basis of English law - it disregards your rights - it's a forced confession
So if stopped for a random test you should ask if it is random. There will be bluster (a bad thing) and threats to arrest you for non compliance - but if you haven't been seen to be causing suspicion then there is no basis to test and if you have a witness to them saying it's voluntary then manufacturing a pretext after that is Very Serious Indeed.
A smart cop would wave you away because a random test can only be voluntary because you haven't caused suspicion and an arrest for failure to supply a roadside sample a breach of the basic tenet of not interfering with law abiding citizens, and thus illegal.
Hands up if you want the police to have the power to stop you in the street/your house/wherever just because they want to because that's what random testing is and it should be resisted because those other things would follow if we let them get away with it.
It's easy enough for them to find a pretext for stopping anyone they like to test - essentially random.
But a truly random test is an erosion of basic liberty. It might seem like no skin off your nose, a minor delay etc but it's OUR law, not theirs and if they break it they should be penalised - but every year they get away with it. It's not as if every other car wont give them grounds for suspicion - not many can drive 'to standard'.
I have been stopped by a bad cop ie one acting beyond their remit. Jumped up little Hitlers like that need stamping on. It ended with the copper shouting at/threatening me for something I didn't do - I don't deserve that. He was throwing his weight around because he felt like it and could get away with it because there were no witnesses and it was his word against mine - if stopped these days the smartphone would go to record. It wasn't a night in the cells but putting someone in fear of their liberty is serious. He got away with it.
You don't want the police 'getting away with it' - those are the words you apply to criminals, which they can be, even if they think they're being fine, upstanding supporters of the public's safety.