Licensees could be forced to allow children on to their premises following a court ruling in the Republic of Ireland earlier this month.
A court ruled that it was against European Human Rights legislation for publicans to refuse entry to children accompanied by their parents at any time.
If the decision is upheld in the UK, it would effectively override Children's Certificates and leave licensees unable to refuse entry to under-18s.
Trade groups in Ireland are now planning to challenge sections of the equality legislation in the courts.
During the landmark court case, an equality officer ruled that such restrictions amounted to discrimination, and that publicans must serve adults who are accompanied by their children "in all circumstances".
He awarded 2,539 euros compensation to a customer who was refused service in a Dublin pub because he had his 13-year-old son with him.
The decision has outraged publicans, who have also been ordered to remove all signs stating that children are not allowed on their premises after certain times.
The prospect of a similar ruling being made in Britain has worried the trade. Bill Sharp, chairman of the National Parliamentary Committee of licensees, said: "This is very serious. It's taking away the right of the publican to use his own discretion for his particular business. There are some businesses that definitely wouldn't be suitable for children. This is a retrograde step and if there was talk of it happening over here we would fight it tooth and nail."