For all motoring offences which carry an endorsement magistrates have the option of awarding penalty points or a disqualification. If they award a disqualification then no penalty points are added to the licence.
So, for example, you could have nine points and commit a speeding offence. The justices can either (a) award more points (the minimum is three) or (b) disqualify you for the latest offence alone.
If they award points you become a “totter” (assuming all the offences were committed within three years) because you have twelve points. This makes you subject to a mandatory minimum disqualification of six months. This disqualification is for “totting” and not for any individual offence.
If they award a disqualification, then your licence will retain the nine points it had when it is returned to you.
Some offences (such as drink-driving and dangerous driving) carry a mandatory disqualification. This will be imposed (as in your son’s case) and will have no bearing on “points” at all.
In short, for any single offence magistrates either award points or a disqualification – not both.
Nonetheless, because he has no points, this does not mean that your son has a “clean” licence. As has been said, the drink-driving offence will remain on his licence for eleven years and must be disclosed to his potential insurers. A second drink-driving offence within ten years of the first will lead to a mandatory minimum disqualification of three years - and a considerably greater fine or possibly a community penalty or even imprisonment (depending on the level of alcohol).
One further point possibly worth a mention is that if a driver accumulates six points on his licence within two years of passing his test he reverts to provisional licence status and has to retake his test entirely (including the theoretical test). <