When does an employee's social media comment cross the line?

The public attention around Antoinette Lattouf's dispute with the ABC has brought into sharp focus the right of an employer to take action if an employee posts social media comments contrary to the policies, directions or interest of the employer. But what are the rules? When will there be valid grounds for an employer to dismiss an employee for such conduct, including other behaviours that take place outside of the usual work hours?

Out of hours conduct and the sufficient connection to work

The courts and tribunals have made it plain that the critical issue to determine whether an employer can discipline an employee for conduct outside of work is whether the conduct has a sufficient connection to the workplace.