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. An explanation of the abbreviations can be found in 'The road user and the law'.
 

Although failure to comply with the other rules of the Code will not, in itself, cause a person to be prosecuted, The Highway Code may be used in evidence in any court proceedings under the Traffic Acts (see 'The road user and the law') to establish liability. This includes rules which use advisory wording such as ‘should/should not’ or ‘do/do not’.

Knowing and applying the rules contained in The Highway Code could significantly reduce road casualties. Cutting the number of deaths and injuries that occur on our roads every day is a responsibility we all share. The Highway Code can help us discharge that responsibility. Further information on driving/riding techniques can be found in ‘The Official DSA Guide to Driving - the essential skills’ and ‘The Official DSA Guide to Riding - the essential skills.’© Crown copyright

The Highway Code : Directgov - Travel and transport