The intricate formula for calculating tuition rates for some British students is facing a legal challenge under the European Convention on Human Rights. Phil Shiner, a lawyer, already represents two English students who have challenged the legality of the steep tuition increase that will take effect next year at universities in England, the BBC reports. And now, it says, he is taking on the pricing practices of Scottish universities.

Scottish residents who study in Scotland do not pay tuition, but students from elsewhere in the United Kingdom are assessed a fee of £1,820 for the coming academic year—a discount of more than a third off what they would be charged in England. Scottish universities plan to retain free education for home students but may follow the lead of their English counterparts and begin charging £9,000 fees, which, under the existing system, would apply only to students from elsewhere in Britain. European Union rules require students from other member states to pay the same rate as local students do, meaning that students from any of the bloc’s 26 other members also enjoy free higher education in Scotland, unlike students from England, Northern Ireland, and Wales.