Workplace privacy in the US is getting a new set of clothes

Significant developments in workplace privacy law and policy in the US over the past year have left employers with a number of new obligations. Litigation in state and federal courts, state legislation and federal agency actions have all led to increased protections for employees, requiring employers to carefully consider and, as necessary, revise their workplace privacy policies and procedures.

I am not sure exactly which laws these are? Any links to relevant laws would be really appreciated!