The Central Administrative Court has ordered Suankularb Wittayalai School to accept 10 students to study at Matthayom 1 level (Grade 7) under area quota for the 2019 academic year.
The ruling, read on Thursday and released on Sunday, responded to lawsuits filed by parents of students who earlier this year applied under area-based quotas but were rejected by this prestigious all-boys school.
Suankularb, together with other state-run secondary schools, is required to give special admission to students whose homes are nearby.
However, the school had turned down scores of applications despite the children living within the specified radius. In March, 11 parents took the matter to the Central Administrative Court.
In handing down its verdict, the court explained the selection committee's process was unlawful because it did not seek the school director's final approval of its deliberations.
By law, the "school director is the only official authorised to make final decisions" on whether to admit students, according to the verdict.
But the court did not find the school guilty of double standards or unlawful actions as accused by the parents.
The judge said Suankularb Wittayalai School has a right to prevent students living in other areas from taking advantage of the quota.
The court, however, dismissed one lawsuit after a check found the family does not live in the same area as the school.