Home Secretary David Blunkett is downgrading cannabis from a class B to class C drug, which will effectively decriminalise its possession.
Police will still be entitled to arrest for possession of cannabis if there are specific aggravating factors, such as smoking in front of minors or outside school gates.
This week Education Secretary Estelle Morris rejected claims from a south London MP that the relaxation of police policy towards cannabis in Lambeth meant pupils as young as 10 were arriving at school "zonked" on the drug.
She told the Commons education select committe: "It would be wrong for anybody to pretend that the English state school system is full of children bombed out of their heads.
"We take seriously any drug-taking in schools or children who go to school under the influence."
While the move has been generally welcomed, representatives from teachers'
unions were wary. Doug McAvoy, general secretary of the National Union of Teachers, said: "Millions of parents who believe - with justification - that drugs are not being pushed in their children's schools, may now have reason to fear this may change."
David Hart, general secretary of the National Association of Headteachers, said: "If the Government is going to decriminalise, it has to be accompanied by very, very tough penalties for dealing. The Government should support schools which have a no-tolerance attitude."
Independent schools often assume a zero-tolerance attitude: most request parents to withdraw pupils, if possession is proven.
And, recently, the Edinburgh Academy hit the headlines for introducing a policy of random drug-testing.
Cannabis, The Issue, Friday magazine, 15