The Constitutional Court has ruled in favour of the University of the Free State's (UFS's) language policy.
The UFS adopted a new language policy in March 2016, which replaced Afrikaans and English as parallel mediums of instruction, and made English the primary medium.
Chief Justice Mogoeng Mogoeng, in a majority ruling on Friday, denied AfriForum's application for leave to appeal a Supreme Court of Appeal (SCA) ruling from March this year, also in favour of the policy.
Mogoeng said the policy was lawful.
The SCA had upheld the university's appeal against a high court order that said the policy decision was unlawful.
AfriForum and Solidarity had initially brought the high court order application to review and set aside the adoption of the policy.
The university's main reason for departing from the parallel-medium policy was that it had the "unintended consequence" of segregating white Afrikaans-speaking students from black students who had chosen to study in English. It led to racial tensions, as well as staff and student complaints.
The high court had held that, in adopting the new policy, the UFS had failed to consider the Constitution and the 2002 Higher Education Language Policy.
The Constitution guarantees language of choice in public education institutions when "reasonably practicable", while the Higher Education Language Policy advocates the retention and strengthening of Afrikaans at historically Afrikaans universities, such as the UFS.