Head teachers, some teachers unions and the Tories all attacked her for diluting the anti-drug message to children.
Ms Morris told a conference on Monday that pupils who sold drugs at school should be expelled but drug education within the school should be an option for those "simply found with cannabis in their pockets".
John Dunford, the general secretary of the Secondary Heads' Association, said exclusion was a vital weapon in maintaining discipline. "There is enormous pressure from governors and parents to make schools a drug-free zone, and he Government should support schools doing that," he said.
David Willetts, the shadow Secretary of State for Education, accused Ms Morris of "undercutting the position" of head teachers. He told BBC Radio 4's Today programme: "If a head wants ... zero tolerance at his or her school they should be free to do so." But Ms Morris responded by quoting the Tories' own guidance to schools - which echoes her comments. That guidance, due to be updated by the Government this week, said: "The fact that certain behaviour could constitute a violation of the criminal law should not ... automatically lead to exclusion."
Ms Morris said: "Tory ministers made clear that they did not expect permanent exclusions in all cases and suggested that schools should have a repertoire of responses."
The Government was committed to tackling the menace of drugs in schools, which was why it was investing pounds 22.5m in drugs education over the next three years, she said.
John Findlay, the Unison national officer representing educational social workers, backed Ms Morris. "It is too simplistic just to say that the kids should be excluded, that the problem should be put back on to the streets ... We need to keep these kids included in the system so that this issue can be dealt with properly."
Gill Astarita, of the drugs charity Addaction, said schools should offer a more positive response than simply washing their hands of each case.Reuse content