Workplace privacy is increasingly becoming an area of legal contention. With the rise of social media and the tendency of people to place many private details of their lives online, employers and prospective employers are becoming more and more interested in learning about their employees through social media. The employee wants work and personal life to be separated; the employer knows that the actions of the employee reflect on the company and feel the need to have a minimum level of observation in the employee's private life.
The most important thing about employee privacy is that without cause, there should be no legal right of an employer to deliberately pry into private affairs. If it is the employer's policy to conduct a thorough background check, that should be stated up front. Otherwise, the check might not be legal. However, a Google search for the employee's name is legal, and monitoring with social media is increasingly common though hard to prove.