Pupil power is to take a new leap forward, with the Government set to consult on giving under-18s the right to appeal against permanent exclusions from school.
But teachers' leaders warn the move would go too far and create "confusion", more appeals and overwork. They want "a line drawn" on how much of a say pupils are given.
Ministers are also looking at giving pupils power to appeal against decisions about school places and levels of support for special needs.
The Government plans to consult on the changes early next year.
The plans follow the passing of a new law that forces schools to consult pupils on everything from the way they are taught to behaviour and uniform policies. At present, it is parents who have the right to appeal against permanent exclusions.
The proposals were revealed by Baroness Morgan, children's minister, who said: "It is our intention to consult on giving pupils under 18 their own right to appeal in their exclusion proceedings, within the wider context of other appeal forums including appeals to the Special Educational Needs and Disability Tribunal and admissions."
But John Dunford, general secretary of the Association of School and College Leaders, said he was opposed to all three. "I think it will lead to more spurious appeals and more work for heads," he said.
In a letter seen by The TES, Baroness Morgan says the move has been partially prompted by a report from the United Nations Committee on the Rights of the Child in October. It set out concerns that children had no right to appeal against exclusions or tribunal decisions.
But Chris Keates, general secretary of the NASUWT, said: "There is an issue of whether there is a line that should be drawn in how far you take this right to a voice for young people. Something that is well intentioned could end up being a complete legal nightmare and create confusion."
Despite strong union and Tory opposition, the parallel move to compel schools to consult pupils on a range of issues was passed in the Commons on Monday, clearing its final parliamentary hurdle.
Baroness Walmsley, Liberal Democrat schools spokesman, who proposed the new law and pushed for pupils' right to appeal, said: "These matters affect a child's whole life, and it is therefore important that they are engaged in the decision.