Stoned Yesterday. Banned Today

Cannabis, Cocaine & Alcohol Driving in Ireland: How Long is Too Long?

Is it legal to drive after smoking cannabis in Ireland?

Not if there’s more than 1 nanogram per millilitre of THC in your blood.

That’s the ‘per se’ limit set in the Road Traffic Act 2016.

"The legal limit for benzoylecgonine is 50ngs.

And the mean level for it was a whopping 1032.9ng,

more than 20 times the legal limit.

That means the average person caught

was nowhere near “just over”.

They were way over"

The Gardai don’t have to prove you were impaired: just that your blood THC level was above that limit.

While we’re on this…

What does “per se” mean in Irish road traffic law?

In plain English: the number is the offence.

If you’re above the per se limit, that fact alone is enough to convict you.

The Gardaí do not have to prove you were impaired.

It’s a strict, numerical cut-off — like a speed limit.

Whether you feel fine or not makes no difference.

For cannabis, the per se limit is 1 nanogram per millilitre of blood THC.

Go over it, and you’re going to be prosecuted for drug driving, no matter how well you were driving.

What is the legal limit for drug driving?

You might think that if you’re “high” you’re over, and if you feel fine you’re under.

The MBRS 2023 Annual Report says otherwise:

• The legal limit for THC is 1ng/ml.

• The median THC level in cannabis-positive drivers was 6.3ng/ml — more than six times the limit.

• THC acid levels were also very high, showing recent use.

What about other drugs?

The Bureau reports that alcohol is the most frequently detected intoxicant in drivers.

The median alcohol level in blood was 153mgs, more than 3 times the legal limit.

And urine? The median level here was 196mgs, almost 3 times the legal limit.

The Bureau said that the 3 most commonly detected drugs were cannabis, cocaine and benzodiszepines. As discussed, the median level was 6.3ng, more than 6 times the legal limit.

"The Bureau reports that alcohol is the most frequently

detected intoxicant in drivers.

The median alcohol level in blood was 153mgs,

more than 3 times the legal limit.

And urine? The median level here was 196mgs,

almost 3 times the legal limit"

For cocaine the number was 60.5ng, more than 6 times the limit.

But it was worse in the case of benzoylecgonine.

Benzoylecgonine is a substance found in the body after someone uses cocaine.

It’s what the liver breaks cocaine down into.

The legal limit for benzoylecgonine is 50ngs.

And the mean level for it was a whopping 1032.9ng, more than 20 times the legal limit.

That means the average person caught was nowhere near “just over”.

They were way over.

What’s ‘Median’?

When the MBRS talks about a ‘median’ level, it’s not quite the same as an average.

The median is the middle number when you line up all the results from lowest to highest. Half the drivers are above it, half are below.

It’s useful because it isn’t dragged up or down by a few extreme cases, so a median of 153mg/100ml means that in a typical case, the driver was about three times the legal limit.

So, for those people with benzoylecgonine in their system, it means that there were a lot of people who had far more than 20 times the legal limit for that drug in their system.

But I feel fine the next day; doesn’t that mean I’m under the limit?

No.

Feeling fine is not the same as being legally under.

THC can remain in your system long after the psychoactive effects fade.

For regular or heavy users, residual THC can keep you over the limit for many hours, sometimes days.

The MBRS isn’t guessing here; it measures exact nanogram levels in every blood specimen.

Do Gardaí test for cannabis often?

Yes.

In 2023:

• Cannabis was the most detected drug in Irish drivers.

• It appeared in 53% of roadside oral fluid positives (Securetec DrugWipe 6S).

• Many cannabis cases also involved other drugs, like cocaine, benzodiazepines or alcohol.

Can I be over the limit if I smoked the day before?

Absolutely. Especially if:

• You’re a frequent user.

• You smoked a large amount.

• You used high-THC strains or concentrates.

Because the legal limit is set so low, even trace amounts above 1ng/ml can mean an automatic prosecution and possible disqualification.

"For those people with benzoylecgonine in their system,

it means that there were a lot of people who had

far more than 20 times the legal limit

for that drug in their system"

How low are the legal limits?

Let’s put it this way, they’re set at the level where the presence of the substance in your system could be explained due to passive inhalation.

In other words, really, really low.

What’s the penalty if I’m caught?

If you’re over the per se drug limit:

• Minimum 1-year disqualification (first offence).

• Higher for repeat offences.

• Fine and criminal conviction recorded.

• 
  

And no, saying “I felt fine” or “I wasn’t impaired” is not a defence.

"How low are the legal limits?

Let’s put it this way, they’re set at the level

where the presence of the substance in your system

could be explained due to passive inhalation.

In other words, really, really low"

Conclusion

The MBRS data makes one thing clear: many cannabis users caught driving in Ireland are far above the legal limit, and the law doesn’t care if you “felt fine”.

So it’s important to get good, experienced road traffic advice.

Exceeding the legal limit on paper is just that: on paper.

Convictions, if they happen, occur in court, not on a summons.  

There’s a big difference between them both.

So, you do have choices.

After all, it’s the choice between going off the road or driving home.

And everyone wants to drive home.