Teachers were given new guidelines today on how to detect GCSE and A-level coursework cheating by their pupils - and told that they could be guilty of misconduct if they accept plagiarised work.
A six-page leaflet, published by the Qualifications and Curriculum Authority, offers advice on how to determine when pupils have had help from outside the classroom.
But teachers are to be given no new guidance from the QCA about the precise level of help with coursework that constitutes malpractice.
Critics said this means teachers remain in the dark about the legality of practices such as allowing pupils so many drafts of essays that the final coursework is effectively the teacher's.
It was also not clear from the leaflet how sanctions could be imposed on a teacher who allowed pupils to plagiarise.
The guidance, Authenticating coursework: a teacher's guide, reminds staff that pupils should know the rules on coursework, and offers a checklist of potential characteristics of plagiarised work. For example, they should look out for work of a higher standard than expected or unusual words or phrases.
Staff are advised to report the pupil to the exam board if they decide that the work is not original, and the candidate has signed a declaration to say that it is. But if the pupil has not signed, there is no duty to report - and the school's own disciplinary procedures will have to be followed.
The guidance follows a QCA report last year which confirmed that cheating by students and parents was widespread and that teachers were helping pupils by writing detailed essay plans and redrafting work.
The report, in November, said: "The rules on teacher advice, redrafting and interim marking are limited and open to interpretation". It said teachers were confused on this issue and more guidance was required.
However, a QCA spokesman said this week that there were no immediate plans to publish such guidance.
Writing under the pseudonym "Derek Fisher", a head of sociology suggested in last week's TES that teachers are now routinely doing pupils' coursework for them. He said: "We need to know what is allowed and what isn't. The QCA probably should have made some decisions about drafting and redrafting."
Sue Kirkham, a QCA board member and president of the Association of School and College Leaders, who led the advisory group on the guidance, said the group had considered the issue of redrafting coursework.
But it had opted to put a document out which was clear, concise and relatively brief.
* The head of Britain's biggest exam board today warns ministers not to overreact to plagiarism by scrapping GCSE coursework in many subjects.
Mike Cresswell, writing in today's TES, comes after Ruth Kelly, the Education Secretary, was responding to the QCA's report on coursework by suggesting that coursework should only be used where it was needed to judge skills that could not be assessed in conventional exams.
Mike Cresswell, opinion 21
Authenticating Coursework: A teacher's guide, www.qca.org.uk courseworkleaflet
Tackling cheating Key points from the new QCA guidance
* Make sure that pupils understand the rules on coursework cheating
* Consider setting pupils "personalised" coursework tasks to stop them copying from each other
* Check whether the work is better than would normally be expected. Does it feature words and phrases they would not normally use?
* If you have suspicions, ask the pupil to give their sources and check popular coursework cheating websites
* If you believe the coursework is not the pupil's own, and the pupil has signed a declaration that it is, report them to the exam board
* If they have not signed a declaration, follow your school or college's rules on coursework cheating