A conviction that, after a specified number of years known as the rehabilitation period, may in all subsequent civil proceedings be treated as if it had never existed (Rehabilitation of Offenders Act 1974). The length of the rehabilitation period depends on the gravity of the offence, and some convictions are not subject to rehabilitation (e.g. when the sentence was life imprisonment). Dismissal from a job on the grounds of an undisclosed spent conviction may amount to unfair dismissal. Similarly, to deny that one has been convicted if the conviction is spent does not amount to perjury or deception. Malicious publication of statements about a person's spent convictions can make the publisher liable for defamation, even if the statements are true. The provisions relating to spent convictions do not apply in criminal proceedings, but counsel and the court should, as far as possible, avoid referring to a spent conviction and references to it in open court may only be made with express leave of the judge in the interests of justice. A spent conviction in a record should be marked as such. See also Criminal Records Bureau.