Why mediation does not work...

Because of the serial bully's Jekyll and Hyde nature, compulsive lying, charm and plausibility, the validity of this person's testimony cannot be relied on in disciplinary proceedings, appeal hearings, and under oath at tribunal and in court. Emphasise this when taking action.

Mediation with this type of individual is inappropriate. Serial bullies regard mediation (and arbitration, conciliation, negotiation etc) as appeasement, which they ruthlessly exploit; it allows them to give the impression in public that they are negotiating and being conciliatory, whilst in private they continue the bullying. The lesson of the twentieth century is that you do not appease aggressors.

The disordered thinking processes of the criminal / antisocial mind are succinctly described in Stanton E Samenow's book 'Straight talk about criminals'. For example:

"Certain people who I term non-arrestable criminals behave criminally towards others , but they are sufficiently fearful [and knowledgeable of the law] so that they do not commit major crimes. We all know them: individuals who shamelessly use others to gain advantage for themselves. Having little empathy, they single-mindedly pursue their objectives and have little remorse for the injuries they inflict. If others take them to task, they become indignant and self-righteous and blame circumstances. Such people share much in common with the person who makes crime a way of life. Although they may not have broken the law, they nonetheless victimize others." (Chapter 8, The criminal mind exists independent of particular laws, culture or customs)

In Samenow's 1984 book 'Inside the criminal mind' he uses this description:

"Some criminals are smooth rather than contentious, ingratiating rather than surly, devious rather than intimidating. They pretend to be interested in what others say. Appearing to invite suggestions, they inwardly dismiss each idea without considering its merits. They seem to take criticism in stride but ignore it and spitefully make mental note of who the critic was. They misuse authority and betray trust but are not blatant about doing so. With the criminal at the helm, employee morale deteriorates. His method of operation sooner or later discourages others from proposing innovative ideas and developing creative solutions." (Chapter 6, Work and the criminal)

From: http://www.bullyonline.org