Three children this week launched a High Court challenge for the right to take a bus to their nearest Welsh language school.
Their lawyers accused a local authority of attempting to "completely re-write school transport law" by denying them free transport to the school.
The three pupils attend Ysgol y Preseli, Pembrokeshire, but live just over the county border in Ceredigion. The school bus goes past the homes of Byron Rees, 11, Matthew Eifion Jones, 13, and Aled James, 13, each morning.
But they have to rely on lifts from their parents despite the fact that, in some cases, their older siblings travel for free.
Nicholas Bowen, appearing for the children, argued that Ceredigion county council was flouting the law by providing free transport for some pupils but not others. The application for judicial review is being seen as a test case for parents throughout Wales who want their children to have the right to travel to the nearest school that provides Welsh language education - even if it is in another county.
Pembrokeshire county council used to run a bus service, taking children from Ceredigion, but stopped giving them free transport last year and is under no legal obligation to do so.
Mr Bowen argued that Ceredigion was under a duty to transport them to Preseli because it was the nearest suitable Welsh language school, being only seven miles from their homes.
Ceredigion is offering to bus the children to Dyffryn Teifi, which is in their own county - but some 17 miles away. Council lawyers argue that the offer meets its legal obligations.
Nigel Giffin, appearing for Ceredigion, said it had no obligation to fund a bus service to Ysgol y Preseli. The key issue was whether pupils would be unable to attend school without the desired transport, which Mr Giffin said did not apply in this case.
Ceredigion, as the pupils' local education authority, has stressed that it has an efficient bus service to Dyffryn Teifi, where places are on offer.
Mr Giffin told Mr Justice Collins: "The local authority has to look at all the circumstances and decide whether it is necessary to provide transport to facilitate that pupil's attendance."
If the transport was not needed to secure school attendance there was no legal duty under the 1996 Act to offer it, said the barrister.
Mr Giffin told the court: "There is a suitable school available. There is transport laid on to that school."
But Mr Bowen said the Ceredigion argument was flawed because, if free transport was not provided to the nearest suitable school for children living beyond a walking distance of three miles, parents could not be prosecuted for failing to send their children to school.
Mr Justice Collins reserved his judgment, indicating that he would give his ruling soon.