First, the thing worth hearing before anything else: a flagged swab is an accusation, not a verdict. It is not what decides your case.
The roadside swab screens. The evidential blood sample decides.
It can come back clear. That is not wishful thinking — it happened to the founder of this site: swab flagged at the roadside, blood completely clear, no charge at all. The safeguard is real and it works in both directions.
The stages
What actually happens, in order
The swab flags at the roadside. You are arrested. This is the screening stage and nothing is decided here.
A blood sample is taken at the station by a healthcare professional. You are entitled to free independent legal advice at this point, at any hour. Take it.
The sample goes to a laboratory. Then you wait, and this is the stage nobody prepares you for.
A charge decision is made on the laboratory result. If you are charged you will be told. If the case does not proceed, you may simply never be contacted.
If charged, the case goes to the magistrates’ court. The offence is triable only summarily, so it stays there.
On timescales
This page deliberately does not give you a number for how long the wait is. It varies a great deal between forces and laboratories, and a confident figure here would be as unreliable as a confident figure anywhere else on this site.
What is fair to say is that it is routinely far longer than people expect. Plan your life around not knowing for a while, and ask your solicitor for the realistic picture in your area.
The waiting
What it costs even when you win
The founder of this site has been swabbed twice. The second time — pulled over for a broken wing mirror — the swab flagged and the blood came back completely clear. No charge. Cleared outright.
But the clear result took months to arrive, and nobody wrote to say so. He found out it was over because it was over.
For all of that time he did not know whether he still had a licence, a job, or a life the same shape as the week before. That is the part of this process people are never warned about, and it happens to people who have done nothing at all.
If you are in that gap now: it is not a sign of anything. It is how long the laboratory and the paperwork take.
Why cases get dropped
Cases do get dropped. Here is what that actually means.
The commonest reason by far is the simplest: the evidential sample does not support a charge. It comes back below the specified limit, or clear. The screening test flagged and the evidence did not follow it.
Beyond that, cases can fail on procedure or on how a sample was taken, stored, transported or analysed. Those requirements exist precisely so that a conviction rests on evidence that can be relied on.
What this page will not do is tell you whether any of that applies to you. That question needs somebody who has read your papers, and this site has not. Anything else would be guessing about your case, which is the same failure as guessing about chemistry.
The 2am adverts
“We’ll get you off”
You will meet this industry tonight, because it is very good at being found by people searching at 2am. The pitch is that a charge can be beaten. The price is usually £6,000 or more.
Being fair about it, because it would be easy not to be:
What is true: genuine defences exist. Genuine procedural challenges exist. They are the safeguard working, and a solicitor who finds one has earned the fee.
What is also true: buying a challenge is not buying an outcome. Nothing is guaranteed. And the worst case is entirely real — you can spend the money and still end up with no licence, no job and no savings.
Before you spend money you can’t afford
Ask a proper motoring solicitor a specific question: is there a realistic basis for a challenge in my case? Not “can this be fought” — anything can be fought. A solicitor who will tell you plainly that there isn’t one is worth more than a marketing page that says there is.
This site does not tell you to challenge and does not tell you not to. It is not our business and we are not qualified. Knowledge before court costs nothing.
Where to go next
If you are here because it has already happened, the most useful thing on this site for you right now is probably understanding what the law actually measured — because most people are convicted without ever being told.
If any of this is bigger than driving for you, the numbers at the foot of this page are free, confidential, and used by people in exactly your position.