Most countries and states which allow for school uniform policies to be implemented have sufficient safeguards to protect religious freedoms.
A school’s ban on religious clothing or religious attire would infringe a student’s right to religious practice, and therefore cannot be enforced. School uniform policies have wiggle room to allow for religious freedom of expression.
Schools that have uniform policies prohibiting hats, for example, allow students who wear hijabs or yarmulke’s in the interest of protecting religious freedoms. Therefore, a mandatory uniform policy is clearly compatible with religious freedom of expression.