The government has been urged to consider changing disability discrimination rules judged unfair to children under the age of nine.
Current rules work against younger disabled children
Hertfordshire Education Authority has been found guilty of discriminating against a six-year-old, James Willey.
It involved when he should know which junior school he would be going to.
His family argued successfully that he was being treated less favourably than his able-bodied peers and than older disabled children.
It relates to how the current code of practice and regulations deal with the transfer from one phase of schooling to another of disabled children under the age of nine.
In some cases, because of a loophole in the law, the process is delayed so a school is not found in time for the start of the school year.
Hertfordshire Education Authority said it was merely acting in accordance with the legislation.
The tribunal urged the Department for Education and Skills to consider re-drafting the current regulations.
Julie Maynard, who helped Mr and Mrs Willey bring their case, said the education department had known about the problem at least since 2003, but had done nothing.
"They are telling everyone else to comply with the Disability Discrimination Act, but this ruling says the act itself is discriminatory," she told the BBC News website.
All children under the age of nine with statements of special educational need had been missed out.
"How can they do that?," she said.
"If you said all boys will know where they are going but not girls, there would be an outcry."
She added that for children as young as two years old to have statements meant they were the most severely disabled.
"So you are targeting the most vulnerable group."
Hertfordshire had argued in the tribunal that the delay in naming a school for James had arisen not from a "slavish adherence" to the regulations but his parents' "obstructive attitude" when offered a chance to attend a meeting to review his situation.
The tribunal rejected this and criticised the authority for allowing the stand-off to go on.