The Health and Safety in Employment Act in New Zealand is a criminal provisions act. So employers can be both vicariously and personally liable for actions of their employees. When may an employer be found personally liable for an employee's action, and when might they be vicariously liable?
An example of a case where an employer was found to be personally liable is Linework Ltd v Department of Labour  ERNZ 80. In this case a supervisor didn't pay attention for a moment and an employee was electrocuted while working on power lines.
An example of a case where an employer was found vicariously liable is Department of Labour v Tranz Rail Ltd  DCR 929. In that case the rail company employed an independent contractor to mow the grass. He had the chute towards the footpath, and it shot out a rock which hit a passerby. It was found the contractor should have been supervised.
In both cases, the employer was liable. What factor determines whether the employer is personally or vicariously liable?