Video report by ITV News Consumer Editor Chris Choi
A father who refused to pay a school fine for taking his daughter on holiday during term time has lost his legal battle at the Supreme Court.
Jon Platt, who took his daughter to Disney World in Florida for seven days in 2015, was fined £120 by her school on the Isle of Wight.
Mr Platt challenged the penalty, arguing that the seven year-old had an attendance rate of more than 90%.
Today five Supreme Court justices unanimously ruled in favour of Isle of Wight Council, which took Mr Platt to court in a bid to overturn a High Court judgment in his favour last year.
Delivering the court's decision in a brief statement, Lady Hale said: "Unauthorised absences have a disruptive effect, not only on the education on the individual child, but also on the work of other pupils, and their teachers."
The panel of Supreme Court justices, including the court's president Lord Neuberger, declared that Parliament's intention was that the word "regularly" means "in accordance with the rules prescribed by the school".
Any educational system expects people to keep the rules. Not to do so is unfair to those obedient parents who do keep the rules, whatever the cost or inconvenience to themselves.
Mr Platt's case now has to return to the magistrates' court as a result of the decision.
The businessman has said he was "not at all surprised" to have lost at the Supreme Court and insisted he had "no intention" of pleading guilty when the case goes back to magistrates' court.
Speaking outside the Supreme Court, Mr Platt, who believes he has spent up to £12,000 fighting the case, said the ruling means the state is taking away the rights of parents to make decisions for their children.
"You can no longer make the decision to take the child out of school without permission of the state," he said.
He urged other parents who find the ruling "utterly shocking" to show their displeasure in local elections on 4 May.
I'm pleased that they acknowledged the judgment doesn't go on to say what the school rules should be. Schools need to think very carefully about what these rules should be.
Lady Hale said the rules should be "a matter for the appropriate authorities."
The Department for Education welcomed the ruling "that no child should be taken out of school without good reason."
A spokeswoman told ITV News it is up to individual schools if they want to authorise a term time absence.
She denied Mr Platt's claim that the ruling meant parents of children who are "a minute late to school" are committing a criminal offence.
"As before, headteachers have the ability to decide when exceptional circumstances allow for a child to be absent but today's ruling removes the uncertainty for schools and local authorities that was created by the previous judgment," a DfE statement said.
The evidence shows every extra day of school missed can affect a pupil's chances of achieving good GCSEs, which has a lasting effect on their life chances. We will examine the judgment carefully and will update schools and local authorities as soon as possible so they are clear what the judgment means for them.
After the Supreme Court ruling, Isle of Wight Council said in a statement: "The Supreme Court's judgment provides much-needed clarity about what constitutes regular attendance at school, to schools, parents and local education authorities.
"The Isle of Wight Council will ensure it continues to apply its code of conduct in relation to school absence and in accordance with this judgment."
Background of term-time holiday case:
Jon Platt is prosecuted by Isle of Wight Council after he refused to pay a £120 fine for taking his daughter on a seven-day family trip to Florida in April 2015 without the school's permission
Local magistrates find there was no case to answer
Two High Court judges in London later uphold the magistrates' decision, declaring Mr Platt was not acting unlawfully because his daughter had a good overall attendance record of over 90%
The council urged the Supreme Court to overturn the High Court decision, saying it raised important issues over what constitutes "regular attendance" at school
Supreme Court rules against Mr Platt, who must now return to magistrates' court