All hairstyles to be blended, not stepped. No undercuts allowed. Ponytails permitted, but not rat tails. In some schools, you need an NVQ in hairdressing just to make sense of the rule book.
But do headteachers really have the right to tell pupils how to wear their hair - and to exclude or reject them if they fail to conform?
The High Court is considering the case of a pupil turned away from St Gregory's Catholic Science College in Harrow because of his "cornrow" hairstyle. The legal challenge rests on the assertion that the boy's braids are part of his heritage.
"The court must decide whether this particular hairstyle is an essential part of Afro-Caribbean race and culture," says Yvonne Spencer, of leading education law firm Veale Wasbrough Vizards. "If they decide that it is, there could be a claim for race discrimination."
Government guidance allows schools to set their own rules on hairstyles. But those rules must not infringe equality or human rights law. In past court cases, schools have been able to defend their stance on haircuts and uniform on the grounds that pupils are free to choose another school if they prefer.
However, these cases were brought under the Human Rights Act; the "cornrow case" is the first to be brought under the new Equality Act, which came into force last October.
If schools are to stay the right side of the act, they must have a hairstyle policy that is clear and unambiguous, and which does not disadvantage pupils of a particular faith, background or gender. It may still be acceptable to ban fads and fashions, but other guidelines are potentially tricky.
Preventing Rastafarians from having dreadlocks, for example, could amount to religious discrimination, while allowing braided hair for girls but not boys might be contested on grounds of gender equality.
And how should schools deal with those who break the rules? Is it really acceptable to exclude a pupil over something as trivial as a bleached fringe? The latest Government guidance states that exclusion is "not an appropriate response" to hair or uniform breaches, except in the case of persistent offenders.
"If a pupil turns up one day with a shaved head, you probably can't justify sending that child home," says Oliver Kean of The Key; an advice service for school leaders. "It's a one-off act, and unlike most uniform offences, it's not something the pupil can rectify immediately."
Of course, if it is a styling issue that could easily be put right, and the pupil refuses to do so, that is a different matter. "It then becomes a behavioural problem, rather than a uniform problem," says Sue Marooney, head of Durrington High in West Sussex, where a Year 9 pupil recently proved reluctant to remodel his "mini-mohican".
"I wouldn't exclude someone over their hair, but I might get them to work in isolation until they agree to get it sorted. We are happy for pupils to express themselves freely through art, music and drama - just not through their haircut."
For school uniform guidance, visithttp:bit.lylqD3ut - Take care not to ban hairstyles associated with a particular race or religion. - Different hair rules for boys and girls could breach sex discrimination laws. - Invite parents and pupils to consult with the school if unsure whether a style will be acceptable. - Pupils can be sent home to change their hairstyle, if it can be done easily and quickly. It should be marked as authorised absence.
What to do
- Take care not to ban hairstyles associated with a particular race or religion.
- Different hair rules for boys and girls could breach sex discrimination laws.
- Invite parents and pupils to consult with the school if unsure whether a style will be acceptable.
- Pupils can be sent home to change their hairstyle, if it can be done easily and quickly. It should be marked as authorised absence.