Driving that falls far below the standard of a careful driver.
Technically it’s a little more than that, but in general that’s about it.
And danger. That's important.
Your driving must be of a type that exposes people to danger, or the risk of it.
The driving has to be such that a reasonable man,
looking at all the circumstances, would recognise the driving as
“involving a direct and serious risk of injury to others”.
The generally accepted definition is driving that falls far below (this is important) what would be expected of a competent and careful driver.
If the driving just falls "below” what would be expected of a competent and careful driver its probably Careless Driving.
But if it falls "far below” it’s Dangerous Driving.
But something else is required.
There must be an element of very bad driving involved.
In the Supreme Court case of People v Patrick Quinlan  the court stated that the driving had to be of such a quality that it “exposed people to peril”.
The driving had to be such that a reasonable man, looking at all the circumstances, would recognise the driving as “involving a direct and serious risk of injury to others”.
This view (of what constitutes dangerous driving) was reaffirmed fifty-five years later in the Supreme Court case of DPP v O’ Shea (2017).
So, in general what constitutes Dangerous Driving?
Here are some examples.
They’re not exhaustive (there are many others) but these give a flavour:
· Aggressive driving (such as sudden lane changes or cutting into a line of traffic)
· Racing or competitive driving.
· Speed that is highly inappropriate for the road or traffic conditions.
· Disregarding traffic lights or other street signs which, on an objective analysis, would appear to be deliberate.
· Driving a vehicle knowing that it has a dangerous defect.
· Driving a vehicle with a load that is dangerous to other road users.
· Holding a mobile phone (or other electronic device) when the driver was avoidably and dangerously distracted by the device.
. Driving when too tired to stay awake or where the driver is suffering from impaired ability (e.g. having an arm or leg in plaster) or impaired eyesight.