Turkey's main pro-secular opposition party has asked the Constitutional Court to overturn a reform allowing headscarves in universities.
Secularists fear there may be further headscarf reforms
The Republican People's Party said the reform violated the secular principles of Turkey's constitution.
The reform - approved by parliament earlier this month - has prompted major controversy in Turkey.
Many secularists in the country equate the wearing of the headscarf with political Islam.
The issue has split Turkey's educational establishment.
Last week the country's president approved constitutional amendments that the governing party said should have allowed female students to start attending universities wearing scarves from this Monday.
But in practice, only a small proportion of the country's universities have allowed girls wearing scarves to attend classes.
Many members of the country's higher educational board and individual university rectors have promised to defy the reform.
They argue that before it can be brought into force, specific new regulations should also be introduced, stipulating exactly how it should be interpreted and implemented, including spelling out what kind of headscarves should be allowed.
The government had originally promised to introduce such measures, but has yet to do so.
Staunch secularists fear that if students are allowed to attend universities wearing scarves, this could lead to a relaxation of the ban on headscarves in public offices and the civil service and increased pressure on all women to cover their heads.
Turkey's ruling party, which has Islamist roots, argues the headscarf ban unfairly bars large numbers of girls from higher education in a nation where about two thirds of women wear the scarf.
The issue remains highly emotive.
And the appeal to the Constitutional Court suggests the battle over the headscarf issue is far from over.