-While I cannot recall the exact legal aspects, years ago while I was the union representative at the engineering company I worked for, the company wanted (for very valid reasons) to go through a number of E-mails sent to/from a couple of specific employees.

The E-mails were eventually read - but in the presence of the employees in question and their (chosen by them, paid by the company) legal counsel.

I can not imagine an employer going to such lengths to accommodate the employees unless required by law to do so. This was in Norway.