How examiners decide what to mark

The DL25 tells you what gets marked. This is the examiner's own guidance on how they decide — published by DVSA as the guidance for driving examiners carrying out driving tests, usually just called DT1. Reading it changes how you run a mock test, and it gives you something far better than "that would probably be a minor" when a pupil asks. (Definitions from DVSA examiner guidance, Crown copyright, reproduced under the Open Government Licence — the source pages are linked above.)

The three fault definitions

• Driving fault — one that "falls short of or deviates from the defined outcome of the standard of driving of a safe and competent driver."
• Serious fault — one that is "potentially dangerous or entails a breach of the law."
• Dangerous fault — one "involving actual danger to the examiner, candidate, the general public, or property."

The or in the serious definition is the part most trainees miss. A fault does not have to be risky to be serious — breaking the law is enough on its own. Crossing a solid white line, ignoring a mandatory sign, or exceeding the speed limit can be marked serious in otherwise empty conditions, because the legality test is independent of the danger test. That is worth teaching explicitly, because a pupil who believes "nothing was coming, so it was fine" has the wrong model of the test.

The difference between serious and dangerous is potential versus actual. Potential danger is serious; danger that actually materialised is dangerous. Both fail the test, so for the pupil the practical consequence is identical — but the distinction shapes the conversation afterwards.

Habitual faults

The guidance is explicit that a run of driving faults is not automatically survivable:

A candidate who habitually commits a driving fault in one aspect of driving throughout the test cannot be regarded as competent to pass the test.

So the fifteen-driving-faults figure is a ceiling, not an allowance, and it is not the only way to fail on minors. Repetition of one specific fault can be regarded as serious in its own right, whatever the total.

This is the single most useful thing to teach a pupil about marking. Six scattered faults across six categories is a very different test from six faults all under "junctions — observation." The second is a habit, and a habit is what turns into a serious. When you spot a pattern forming in a mock, that is the moment for the conversation, not the debrief at the end.

The three tests examiners apply

DVSA gives its examiners three questions to keep marking consistent. All three are just as useful to you when you are marking a mock.

The first rule of assessment

If the drive was perfect before and perfect after this fault occurred, would this fault and this fault alone cause the candidate to fail their test?

This isolates the fault from everything around it. It stops a good drive excusing a serious error, and equally stops a scrappy drive making an ordinary fault look worse than it was.

The sixteenth fault

If this was the 16th fault, could you justify it resulting in failure?

Applied to every fault regardless of where it happened in the test. It is a consistency check: if you would not be comfortable failing someone on this fault, you should not be recording it. It keeps examiners — and instructors running mocks — from tallying trivia early in a drive and then quietly ignoring the same thing later.

Adding and taking away

Could you add anything to that fault to make it worse? Or could you take away anything to make it better?

A severity gauge. If you can imagine the same moment being meaningfully worse, it probably was not yet serious. If you cannot make it any worse without inventing a collision, you are at the top of the scale.

Using this with a pupil

Three things follow for your teaching:

1. Teach the legality half of "serious". Pupils reason about danger naturally and about law barely at all. Ask "what would make that serious even with an empty road?" and let them find it.
2. Name patterns early, not at the end. The habitual-fault rule means the third repeat matters more than the first. Stop and coach it when you see the pattern, using FISH or the SEDSS questions.
3. Mark your mocks with these three tests. Instructors tend to mark mocks either far harsher or far softer than a real examiner. Applying the first rule of assessment and the sixteenth-fault question out loud makes your marking calibrated — and makes the mock worth something. See conducting mock tests.

Bear in mind that the examiner's decision also has to be defensible on paper: what they write in the fault description on the back of the DL25 is what the pupil reads and what the appeal, if there ever is one, turns on. Marking that you can explain in one clear sentence is marking you have got right.