There are already laws to protect whistle-blowers
The NHS is still not doing enough to encourage a culture of whistle-blowing, a study suggests.
A British Medical Journal investigation found the content of many policies was overly cautious and negative after viewing documents from 118 trusts.
Some used words such as disciplinary too often, while others did not do enough to stress the ability of staff to go to outside bodies with concerns.
The government said it was looking to improve practices.
Whistle-blowing has been a high profile issue for the past year.
Nurse Margaret Haywood was struck off last year after filming examples of neglect at Brighton's Royal Sussex Hospital for a BBC Panorama programme. She has since been re-instated.
This followed the controversy over Stafford Hospital which inspectors criticised for "appalling" standards of emergency care after "patients needlessly died".
Subsequent reports picked up on the lack of whistle-blowing over the years.
The BMJ compared policies to six standards produced by Public Concern at Work, an independent authority set up to encourage whistle-blowing.
It found that four trusts did not even mention that staff could go outside the organisation with concerns, while a third stressed the importance of going through internal procedures.
A fifth did not stress confidentiality would be protected, while a similar number mentioned the threat of disciplinary action with one policy using the term 21 times.
Peter Gooderham, a law lecturer at Manchester University, said staff needed more assurances.
"We need some positive recognition for people who have raised concerns. They shouldn't be treated as troublemakers, ostracising them, suspending them from work and so on."
Dr Mark Porter, chairman of the British Medical Association's consultants committee, agreed there was an issue.
"We get very concerned about doctors who fall foul of these whistle-blowing policies while following their professional duty."
The Department of Health said it was looking to improve standards and would be re-issuing advice on the issue soon.
A spokeswoman said: "There is clear guidance for NHS staff on the right not to be unfairly dismissed for whistle-blowing or reporting wrong-doing."