Matthew MacIver believes that teacher specialisms in particular have to come under scrutiny as a result of changes in schools such as the introduction of Higher Still subjects like philosophy, psychology and sociology.
"We have no teachers in Scotland registered to teach them; but they are still taught. This has created a debate about the relationships between the secondary school and further education colleges," Mr MacIver said.
Anomalies are thrown up by the growing trend towards third and fourth-year pupils being taught vocational subjects in colleges. "These pupils are under 16 and should be taught by registered teachers," Mr MacIver said. "My suspicion is that many are not."
Pressure for reform will also come from plans to have secondary specialists working in primary.
Mr MacIver, addressing secondary heads and deputes, said teachers could gain new qualifications through continuing professional development instead of "going through the hoops needed at the moment to give them registration in other subjects".