Patrick Horan
Ireland's road traffic solicitor
The Cocaine Byproduct That’s Costing Irish Drivers Their Licence
Why Testing Positive for BZE Means You Took Cocaine and Why It Still Leads to Prosecution
You’re not ‘high’.
You’re not impaired.
You’re driving home from work.
But you took cocaine at the weekend, and your body is still carrying the chemical evidence.
"That’s more than 20 times the legal limit
for benzoylecgonine, on average.
And it’s a huge jump in just one year"
It’s called Benzoylecgonine (BZE), the main breakdown product of cocaine.
And under Irish law, if Gardaí take a sample and the Medical Bureau of Road Safety detects it above 50 nanograms per millilitre, you’ll be prosecuted for drug driving.
It doesn’t matter that the cocaine itself is gone.
It doesn’t matter that you feel completely fine.
The presence of this metabolite is enough to convict you.
What is Benzoylecgonine?
Benzoylecgonine is the primary metabolite of cocaine, meaning it’s what your body turns cocaine into after you take it.
According to the U.S. National Library of Medicine:
“Benzoylecgonine is the major metabolite of cocaine. It is formed in the liver by enzymatic hydrolysis of cocaine and has a longer half-life than cocaine itself, making it the primary target in drug testing.”
In plain English: cocaine leaves your system quickly, but benzoylecgonine sticks around much longer.
That’s why labs test for it.
Why Ireland Tests for BZE in Blood
Ireland’s drug driving laws make no distinction between cocaine and its metabolite.
Section 4 of the Road Traffic Act sets a 50 ng/ml limit for benzoylecgonine in blood.
Anything above that is an automatic offence, even without proof of impairment.
The official reason is simple:
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If BZE is in your system, you’ve taken cocaine recently.
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Cocaine use is linked to some of the most serious road safety risks: extreme overconfidence, risk-taking, aggression, and rapid impairment.
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Penalising BZE is a way to detect and punish cocaine use in drivers, even after the “high” is gone.
"Benzoylecgonine doesn’t cause impairment.
At all.
Read that again.
Unlike cocaine, cannabis, heroin or MDMA
which do cause impairment in some way, BZE does not"
The Numbers That Should Make You Sit Up
The Medical Bureau of Road Safety only began reporting average blood levels for cocaine and benzoylecgonine in 2022.
Here’s what they found:
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2022:
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Mean cocaine level: 34.1 ng/ml (limit is 10 ng/ml)
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Mean benzoylecgonine level: 604.6 ng/ml (limit is 50 ng/ml)
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2023:
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Mean cocaine level: 60.5 ng/ml
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Mean benzoylecgonine level: 1032.9 ng/ml
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That’s more than 20 times the legal limit for benzoylecgonine, on average.
And it’s a huge jump in just one year.
Why This Feels Unfair and Where the Law Stands
Benzoylecgonine doesn’t cause impairment.
At all.
Read that again.
Unlike cocaine, cannabis, heroin or MDMA which does cause impairment in some way, BZE does not.
If BZE doesn’t cause a ‘high’, why should you be punished for it?
That’s the ‘fairness debate’ in a nutshell.
And it makes sense.
Most people, including some judges and Gardaí, have never heard of benzoylecgonine.
And when they learn it’s just a by-product, the first question is:
“If it’s not impairing you, why is it illegal?”
The government’s counterargument is public safety:
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Cocaine use among Irish drivers is rising sharply.
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According to the Health Research Board, cocaine is now the most common drug named by people in treatment: over 5,200 cases in 2022, up 250% since 2017.
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The law is designed to take drivers who’ve used cocaine off the road before they cause harm, not just while they’re “high.”
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Remember: BZE can only end up in your blood if you took cocaine.
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If you want to seriously curb cocaine use (and the government does) then targeting people who have its by-product in their blood is one way.
"The law is clear: if it’s there,
and it’s above the limit, you’ll be prosecuted.
And remember, the limit is tiny"
A Rare Legal Principle: You Must Help Prosecute Yourself
There’s another layer to this.
Drug and drink driving laws are one of the few areas in criminal law where you are legally required to assist the police in gathering evidence against you.
You read that right.
If Gardaí require you to provide breath, blood, or urine, you must comply, or you face severe penalties for refusal.
Normally, in criminal law, you have the right to remain silent and avoid self-incrimination.
But in some areas of road traffic law, that right is limited in the name of protecting the public.
The courts have been clear:
No right is absolute. You don’t have an absolute right to refuse a specimen.
Public safety outweighs that freedom, because a driver under the influence is controlling a potentially deadly machine.
A pedestrian just mainly poses a risk to themselves.
International Context
Ireland’s benzoylecgonine limit of 50 ng/ml in blood matches the UK’s.
In the United States BZE is also the primary target in drug testing.
This is especially the case in workplace and probation testing, because it’s easier to detect than cocaine itself.
FAQs
Q: What drugs is benzoylecgonine found in?
A: Only in cocaine. It’s not found in any legal medicine or over-the-counter drug.
Q: What is the limit for benzoylecgonine in Ireland?
A: 50 nanograms per millilitre of blood.
Q: What can make you test positive for benzoylecgonine?
A: Taking cocaine. There’s no other source.
Q: How long after taking cocaine can you test positive for BZE?
A: It depends on how much you took, your metabolism, and other factors, but it can be detectable for days after use.
Q: Does BZE itself cause impairment?
A: No. It doesn’t cause a high. But the law doesn’t require impairment for cocaine-related offences.
The Bottom Line
Benzoylecgonine isn’t a drug you can buy.
It’s not something you take on purpose.
But it’s the reason more and more Irish drivers are being convicted of drug driving, often days after they last used cocaine.
The law is clear: if it’s there, and it’s above the limit, you’ll be prosecuted.
And remember, the limit is tiny.
If that happens speak to an experienced lawyer.
After all, it’s the choice between going off the road or driving home.
And everyone wants to drive home.