What are the defences available to an employee who has posted a potentially defamatory comment about his or her employer on a social networking site?

Generally speaking, an employee will be able to defend a claim of defamation if he or she can show that the statement published:

  • was true or substantially true (regardless of his or her motives for writing it);
  • was an honestly held opinion;
  • was on a matter of public interest and the employee reasonably believed that publishing it was in the public interest; or
  • is covered by some form of legal privilege.

An employee dismissed for breaching the employer's policy on use of social media may allege that he or she believed that the statement was "private". However, several first instance employment tribunal decisions have shown that a mistaken belief in privacy does not provide a reasonable explanation and such dismissals have been found to be fair.