Local authority lawyers are "in a frenzy of speculation", not least because psychologists were in "double jeopardy" by giving advice to authorities, parents and the child.
"Sometimes our advice is at odds," Mr MacPhee said. "European law says parents have a right to a fair hearing and fair evidence, for example, in records of need procedures. These are perceived by parents to give equivalence across Scotland. They do no such thing."
He stated in a conference paper: "The law has already had profound effects on the work of attendance committees and the panel system and we can reasonably anticipate questions regarding our impartiality as professional advisers. The law may have implications in many ways, specifically in terms of how Scottish laws and Scottish Executive guidance is interpreted and written."
Equal opportunities legislation is another possible avenue for litigation that may test psychologists' neutrality, he advised.
Mr MacPhee also proposed afresh structure for psychological services, with a central body to oversee developments and ensure equity across authorities. Council reform had fragmented services, leaving many in peripheral areas short of staff and resources.
"The location of psychologists within a national framework could offer the possibility of answering many concerns regarding professional standards, recruitment, day-to-day management, continuing professional development, supervision and support," he said.
But critics believe such a plan could lead to diktat from the centre and increased bureaucracy.
Ian Liddle, chair of the Association of Scottish Principal Educational Psychologists, said: "Performance indicators and quality assurance for psychology services have just been developed and we need to give that a go." Mr Liddle also pointed out that a Scottish Executive review of psychological services is under way following concerns raised by the special educational needs advisory forum.
Staff shortages and training of new recruits remain the number one concern. "Although we have been producing more psychologists, authorities have been increasing their establishments," Ian Liddle said.