MUST vs should in the Highway Code — which rules are law and which are advice

Every argument about the Highway Code eventually reaches the same sentence: “but that’s only a should, it isn’t the law.” Half of that is right. The Code writes its legal requirements in capitals — MUST and MUST NOT — and everything else in ordinary words, and the difference is real. What the second half of the sentence misses is that an advisory rule is still evidence, and that plenty of rules contain both wordings in the same bullet list. Learn the grammar once and you can settle any of these arguments from the page itself.

Many of the rules in the Code are legal requirements, and if you disobey these rules you are committing a criminal offence. You may be fined, given penalty points on your licence or be disqualified from driving. In the most serious cases you may be sent to prison. Such rules are identified by the use of the words ‘MUST/MUST NOT’. In addition, the rule includes an abbreviated reference to the legislation which creates the offence.

Two wordings, two very different consequences

Nothing else in the Code changes this. Capitals or not — that is the whole test.

How to tell in three seconds

1. Look for capitals. In the Code published on gov.uk, MUST and MUST NOT are always set in capitals when they carry legal force, and a lower-case “must” in ordinary prose is not the signal. Northern Ireland’s Code is the one exception — it prints the same legal requirements in lower case, so there the Law line does all the work. The Northern Ireland section below has the detail.
2. Look underneath the rule for a Law line. Every legal requirement carries an abbreviated reference to the legislation that creates the offence. Rule 124 cites RTRA sects 81, 86, 89 & sched 6; Rule 171 cites RTA 1988 sect 36 & TSRGD schedule 9 parts 7 and 8.
3. Decode the abbreviation if you need to. Annex 4 lists them — RTA is the Road Traffic Act (1984, 1988 or 1991, as indicated), RTRA the Road Traffic Regulation Act 1984, CUR the Road Vehicles (Construction & Use) Regulations 1986, MV(DL)R the Motor Vehicles (Driving Licences) Regulations 1999, TSRGD the Traffic Signs Regulations & General Directions.

A rule with no capitals and no Law line is advice. The same convention runs through all 300-plus rules and every annex, so it is worth two minutes of practice on a chapter you already know.

“Advisory” does not mean “ignorable”

The status of an advisory rule is not a matter of opinion. It is set out in the Road Traffic Act 1988 itself.

A failure on the part of a person to observe a provision of the Highway Code shall not of itself render that person liable to criminal proceedings of any kind but any such failure may in any proceedings (whether civil or criminal, and including proceedings for an offence under the Traffic Acts, the Public Passenger Vehicles Act 1981 or sections 18 to 23 of the Transport Act 1985) be relied upon by any party to the proceedings as tending to establish or negative any liability which is in question in those proceedings.

Two things follow, and both matter.

• Evidence, in civil and criminal courts alike. A breach of an advisory rule can be put in front of a court by any party to establish liability — or to defeat it. Insurers argue this at fault stage; it is how a “should” ends up deciding who pays.
• The conduct can break a different law. Advisory rules describe how a careful driver behaves. Driving a mechanically propelled vehicle on a road without due care and attention, or without reasonable consideration for other persons using the road, is an offence under section 3 of the Road Traffic Act 1988 — unlimited fine, 3 to 9 penalty points, discretionary disqualification. Following too closely is the clearest case: Rule 126’s stopping distances and two-second gap are advisory from start to finish — no capitals, no Law line — and the rule still ends like this.

Tailgating is where the gap between you and the vehicle in front is too small for you to be able to stop safely if the vehicle in front suddenly brakes. Tailgating is dangerous, intimidating and can cause collisions, especially when driving at speed. Keeping a safe distance from the vehicle in front gives you time to react and stop if necessary. Dangerous and careless driving offences, such as tailgating, are enforced by the police.

So “it’s only a should” answers the question is this rule itself a criminal offence. It does not answer can this cost me.

The trap: one rule, both wordings

This is where most arguments go wrong. Rules are not sorted into a legal pile and an advisory pile — a single rule routinely does both, and the split can sit inside one bullet list. Rule H2, the junction and crossing rule introduced with the hierarchy of road users, is the standard example.

At a junction you should give way to pedestrians crossing or waiting to cross a road into which or from which you are turning. You MUST give way to pedestrians on a zebra crossing, and to pedestrians and cyclists on a parallel crossing (see Rule 195).

Two sentences, two different legal statuses. Giving way at a junction is advice. Giving way to someone already on a zebra or parallel crossing is the law, and the Law line beneath Rule H2 names the traffic signs regulations and the Highway Act 1835 among its sources.

Rule 195 draws the same line even more finely, one bullet apart:

you should give way to pedestrians waiting to cross

you MUST give way when a pedestrian has moved onto a crossing

Waiting at the kerb: advice. One foot on the stripes: law. Read to the end of the list before deciding which half of a rule you are quoting.

Speed: Rule 124 is the law, Rule 125 is the judgement

The pairing that produces the most confident wrong answers. Rule 124 states that you MUST NOT exceed the maximum speed limits for the road and for your vehicle, and adds that a limit of 30 mph — 20 mph in Wales — generally applies to all roads with street lights, motorways excepted, unless signs show otherwise. That is a legal maximum with a Law line under it.

Rule 125 is the other half, and it has no capitals anywhere in it.

The speed limit is the absolute maximum and does not mean it is safe to drive at that speed irrespective of conditions.

It goes on to say you should always reduce your speed where the road layout presents hazards such as bends, where you are sharing the road with pedestrians, cyclists, horse riders and motorcyclists, where the weather makes it safer, and at night. None of that is an offence in itself. All of it is the standard a court would measure your driving against — and driving too fast for the conditions inside the posted limit is exactly the conduct section 3 covers.

The short version for the exam: the number on the sign is a ceiling you MUST NOT go through, not a speed you are entitled to hold.

Three more worked examples

The horn — Rule 112 does both in four lines

“Never sound your horn aggressively” is advice. What follows is not: you MUST NOT use your horn while stationary on the road, or when driving in a built-up area between 11.30 pm and 7.00 am — except when another road user poses a danger. The exception belongs to the MUST NOT, not to the advice — though it is the Code’s plain-English summary of a narrower regulation: CUR reg 99 carves out danger from the stationary limb only, and only for danger due to another moving vehicle on or near the road.

Phones — Rule 149 and the hands-free myth

Using a hand-held phone or similar device when driving, or when supervising a learner driver, is a MUST NOT, and the prohibition reaches picking the phone up while stationary in traffic. Hands-free is dealt with in the same rule in advisory wording — “using hands-free equipment is also likely to distract your attention from the road” — which is where the argument usually stops. It should not, because Rule 149 opens with a MUST: you MUST exercise proper control of your vehicle at all times. Losing control on a hands-free call is not protected by the absence of a specific prohibition, and Rule 150 repeats the same MUST for satnavs, driver assistance systems and screens.

L plates — display is law, removal is advice

Annex 3 splits the two in consecutive sentences.

Any vehicle driven by a learner MUST display red L plates. In Wales, either red D plates, red L plates, or both, can be used. Plates MUST conform to legal specifications and MUST be clearly visible to others from in front of the vehicle and from behind. Plates should be removed or covered when not being driven by a learner (except on driving school vehicles).

Displaying them is a legal requirement with a Law line naming the driving licence regulations. Taking them off when a full licence holder drives the car is a should — which is why “is it illegal to drive with L plates on?” gets a different answer from “is it illegal to drive without them?”.

Signs are a third category

A traffic sign can turn advice into an order without the Code changing a word. Signs with red circles are mostly prohibitive and signs with blue circles but no red border mostly give a positive instruction — and where a lawfully placed sign of the prescribed type gives an indication of a statutory prohibition, restriction or requirement, a driver who fails to comply with it commits an offence under section 36 of the Road Traffic Act 1988. Rule 171’s MUST — stop behind the line at a junction with a Stop sign and a solid white line — is that section doing its work.

This is why “the signs win” keeps appearing in rules that are otherwise advisory. Lane allocation at a roundabout is a good example: the general guidance in Rule 186 gives way to painted arrows and signed lane allocation, and our roundabouts guide works through what to do when the two disagree. Learn what each sign shape is doing on road signs.

Northern Ireland

The Highway Code on gov.uk applies to England, Scotland and Wales. Northern Ireland has its own Code, based on the Great Britain version, with differences where road safety legislation differs — and it draws the identical line: rules identified by “must” and “must not” are legal requirements with an abbreviated reference to the legislation, and the Code can otherwise be used in evidence in court proceedings to establish liability, including rules using advisory wording. The one thing that does change is the typography — Northern Ireland prints those legal requirements in lower case rather than capitals, so the Law line under the rule is what marks it. If you are testing in Northern Ireland, our Northern Ireland theory test guide covers what else changes.

Common test questions and the answers

“The Highway Code says you should do X. Is that the law?”

No — not in itself. Only rules worded MUST or MUST NOT are legal requirements. An advisory rule can still be relied on in court to establish liability, and the behaviour it describes may break a separate law, but breaching it is not an offence on its own.

“Is the whole Highway Code the law?”

No. It mixes both: legal requirements written in capitals with the legislation cited underneath, and advice written in ordinary words. Checking for the capitals and the Law line is the fastest way to sort any rule you are unsure about.

“Can you be prosecuted for breaking an advisory rule?”

Not for the breach itself. You can be prosecuted for the underlying conduct if it amounts to an offence — careless or inconsiderate driving under section 3 of the Road Traffic Act 1988 is the usual route — and your failure to follow the rule can be put before the court as evidence.

“A pedestrian is waiting at the kerb to cross a side road I’m turning into. Must I give way?”

You should — Rule H2 words the junction case as advice, and Rule 170 repeats it in the same form, adding that a pedestrian who has started to cross has priority. It becomes a MUST once a pedestrian has moved onto a zebra crossing, or a pedestrian or cyclist onto a parallel crossing.

“Are the hierarchy rules H1 to H3 law?”

H1 and H3 are worded as advice throughout. H2 is the one that contains a MUST, for zebra and parallel crossings. The distinction is about enforcement, not importance — all three are examinable, and the wider set of changes is summarised in what changed in the Highway Code.

“The limit is 60. Can I be done for doing 55?”

Yes, in the right conditions. Rule 124 sets the legal maximum; Rule 125 makes clear the limit is not a statement that the speed is safe. Driving too fast for the road, the weather or the traffic is what section 3 catches, and the posted number is no defence to it.

Where this shows up in revision

The wording is not a side topic — it is the grammar the whole Code is written in, and the multiple-choice questions are drawn from The Highway Code, Know your traffic signs and Driving — the essential skills. Read the introduction to the Highway Code before you read anything else in it, keep the glossary to hand for the abbreviations, work the 14 DVSA topics, and sit a full mock theory test under the real timer. It is free to get started.

Sources

• GOV.UK — Highway Code: introduction — wording of The Highway Code, Rules H1 to H3
• GOV.UK — Highway Code: general rules, techniques and advice for all drivers and riders (Rules 112, 124, 125, 149, 150)
• GOV.UK — Highway Code: using the road (Rules 170, 171, 195)
• GOV.UK — Highway Code: traffic signs — signs giving orders
• GOV.UK — Highway Code: Annex 3, motor vehicle documentation and learner driver requirements
• GOV.UK — Highway Code: Annex 4, the road user and the law — the legislation abbreviations
• GOV.UK — Highway Code: Annex 5, penalties
• legislation.gov.uk — Road Traffic Act 1988, section 38 (effect of a failure to observe the Highway Code)
• legislation.gov.uk — Road Traffic Act 1988, section 3 (careless, and inconsiderate, driving)
• legislation.gov.uk — Road Traffic Act 1988, section 36 (drivers to comply with traffic signs)
• nidirect — Introduction to the Highway Code (Northern Ireland)
• GOV.UK — Theory test: revision and practice

Highway Code excerpts are reproduced under the Open Government Licence v3.0.