Commissioner has backed the use of file markers to highlight the danger posed by certain individuals to employees.
Advice has been published to help those working with the public to manage the use of violent warning markers and comply with the Data Protection Act.
The markers usually take the form of a piece of text attached to an individual's file. The commissioner said they are a useful tool, but must be used correctly to stay within the law.
Deputy Information Commissioner David Smith said: "It is a common misconception that the Data Protection Act prevents the use of violent warning markers.
"This guidance makes clear that employers can use these markers to help protect their staff in the workplace, provided that the principles of data protection are adhered to at all times.
"This guidance will help employers act in the best interests of their workforce while complying with data protection law."
The decision to place such a marker on an individual's file should always be based on a specific incident, and details of that incident must be accurately recorded.