It comes as a legal challenge against the governing body of Aberdare Girls' School in Rhondda Cynon Taf is filed at the High Court by London-based human rights group Liberty.
Sarika Watkins-Singh, 14, was excluded from the school last November after she continued to wear her religious bangle, called the Kara, in defiance of a ruling made by the school's governing body. The ban had been imposed on the grounds that the school's code of conduct states that pupils can only wear a single pair of stud earrings and a wristwatch.
Liberty, which represents Miss Watkins-Singh's family, confirmed to TES Cymru this week that it had filed a legal challenge to the High Court on December 19 after talks with the school failed to reach agreement.
It is claiming the actions of the school's governing body "indirectly discriminate on the grounds of race" and the body has acted against the Race Relations Act 1976, the Equality Act 2006 and the Human Rights Act 1998.
Liberty says the governing body must lodge "its defence" in the High Court by today. No comment was made by Rhondda Cynon Taf local authority this week, with a spokesperson saying "legal proceedings were now active."
A judge from the High Court will now decide whether the case is strong enough to go ahead, as well as considering a request by Liberty for Miss Watkins-Singh to return to school.