While doctors, lawyers, police officers and a whole host of other professionals can be sued for negligence, teachers, educational psychologists and others working for a local education authority seemingly cannot.
The Court of Appeal decision last week has created an anomaly, claim Ms Phelps's lawyers. They are baffled while hundreds of other people with similar claims are distraught.
Solicitor Sharon Burkill, a member of Ms Phelps's legal team, said: "It gives effective immunity to teachers whose primary duty in law now seems to be to the local authority and not to the individual pupil or that pupil's family. It is an unusual immunity to have been granted when other professionals are all accountable for their actions when they make a fundamental mistake."
John Morrell, the lawyer acting for Hillingdon, said the Court of Appeal overturned the case on three basic grounds. First, that the educational psychologist was not negligent. Second, that Ms Phelps failed to prove a different method of teaching would have had "any measurable effect" on her literacy skills. And third - and perhaps most critically in terms of future repercussions - the Court of Appeal "has recognised that it is not the duty of teachers or educational psychologists to ensure the future financial well-being of pupils".
Mr Morrell said the Court of Appeal had now established a clear distinction between the kind of relationship a doctor has with a patient, for example, compared to a teacher with a pupil.
Neville Harris, professor of law at Liverpool John Moores University and editor of Education Law reports, believes only a final decision in the House of Lords will properly clarify the position of teachers in negligence claims.
A 1995 House of Lords ruling had appeared to attach to teachers a common-law duty of care, which for the first time opened them up to negligence claims. The court decision has put severe restrictions on this, but has not overturned it.
"I would not say necessarily teachers, headteachers or advisory teachers are off the hook," said Professor Harris. "The only way it can be satisfied is if it goes to the House of Lords."