No-one can foresee the circumstances in which they could be forced to drive a car after drinking alcohol, the environment minister has said.
The minister said the clear message was to "never, ever drink and drive"
Arlene Foster insisted it was wrong to drink and drive but said the law did recognise mitigating circumstances.
She has outlined a move to reduce the legal alcohol limit for driving from 80mg to 50mg per 100 millilitres of blood in Northern Ireland.
It will be 20mg for inexperienced drivers, motorcyclists and HGV drivers.
The minister was speaking after a senior police officer suggested there could be mitigating circumstances for drink driving officers keeping their jobs.
Deputy Chief Constable Paul Leighton also defended allowing an officer caught drink driving to retain her job.
He said the incident preceded the PSNI's dismissal policy of May 2006.
However, Ms Foster said that she would resign if she was caught drink driving.
She told the BBC's Nolan Show that the police were "bringing anyone caught drink driving before the courts".
"This woman was in front of a court, and to me that is the important factor," she said.
"The law itself says that if you drink and drive you will be subject to a mandatory disqualification.
Constable Donnelly was banned from driving for 12 months
"However, it does make cause for mitigating circumstances. But I have to say that in my former job as a solicitor there were very few times when people did not have a mandatory disqualification."
The minister said the clear message was to "never, ever drink and drive".
On Thursday, Mr Leighton raised the hypothetical situation in which someone who had been drinking being forced to take a sick child to hospital as a potentially mitigating circumstance.
Ms Foster said: "I don't know what I would do in that circumstance... I don't think anybody knows until the set of circumstances present themselves.
"You can't rule it out, and that is what the law says as well."