Head teachers are receiving tougher drug prevention guidelines from the Department for Education and Skills.
The guidance says about a third of 15 year olds are using cannabis
These caused controversy last month when Prime Minister Tony Blair indicated that they would give heads new powers for random drug tests.
Heads had complained there was confusion about how such tests could be applied.
The new guidelines are intended to give heads more support - and more options such as drug tests and searches.
But the guidelines, which replace existing drug advice, make clear that searches for drugs will not mean pupils being frisked.
Head teacher are advised not to use sniffer dogs without police involvement
"It is not appropriate for a member of staff to carry out a personal search. Personal property cannot be searched without consent," the guidelines tell head teachers.
But the guidelines specify that lockers can be searched - "even where consent is withheld".
There is also an endorsement of head teachers' right to use sniffer dogs and drug testing - but it suggests that schools should use "extreme caution" if they plan to use sniffer dogs without police involvement.
In terms of testing, the guidelines note that there are schools which have used urine testing for drugs - and it asserts head teachers' right to decide on such strategies.
But with both testing and searching, it makes clear that these are to be used with great caution in targeted circumstances, after consent has been established, usually with the involvement of the police and not as a randomly-applied deterrent.
The drug prevention guidelines show schools how they can inform pupils about the dangers of using drugs - and there are suggestions for how drug problems in school can be tackled.
It also gives first-aid advice for what teachers should do if pupils appear to be overdosing or suffering from a drug-related problem in the classroom.
The guidelines quote research that says about a third of 15 year olds are using cannabis.
The Prime Minister, Tony Blair, raised the prospect of school drug tests in an interview with the News of the World newspaper last month.
"If heads believe they have a problem in their school then they should be able to do random drug testing," he said.
But this sparked protests and scepticism from teachers' organisations and children's rights campaigners.
The head of the National Association of Schoolmasters Union of Women Teachers warned that there was a lack of clarity about the legality of drug testing.
And the leader of the Secondary Heads Association asked if it was really fair to expect schools to tackle a drug problem that existed in the wider society.
The prospect of legal challenges over drug testing in school were also raised by Carolyn Hamilton, director of the Children's Legal Centre at the University of Essex, which examines policy and law affecting children.
Insisting that pupils take drug tests could be in breach of the rights to privacy in Article 8 of the European Convention on Human Rights, said Ms Hamilton.
"We're very much against random drug testing," she said, both on the grounds of principle and the expense and complexity of how it would be put into practice.