"Legally, both cases center on the interpretation of a 1997 amendment to the Individuals with Disabilities Education Act, which provides that disabled children are entitled to a "free appropriate public education."
That amendment says that parents of children with disabilities "who previously received special education" services in a public setting may be entitled to reimbursement for private-school tuition if their public school did not make free appropriate public education available in a timely manner.
While most of the nation's 6 million special-education students attend public school, the law allows parents to seek public financing for private school if the public schools cannot adequately serve their children. Almost 90,000 students are in private placements, most of them with their public school's agreement.
But increasingly, thousands of families unilaterally enroll their learning-disabled, emotionally disabled or autistic children in private schools — often with staggeringly high tuitions — and then seek reimbursement."
I can surely get possibly needing to go outside of a public school for services. But it does seem like the Act requires (asks) parents to give the public school system an opportunity to meet their needs. That doesn't seem like a lot to ask before going elsewhere. Likewise, the key phrase "in a timely manner" would imply that the district can't stall or switch the student around from school to school in order to put off having to pay for private school services.