...cannot complain...? I need to know what it is formally called, or how this is described and labeled under.
The situation is:

Two employees at any given company. One has a complaint about the other's PERFORMANCE/ (or otherwise attitude, behavior,etc.). The 1st employee complains DIRECTLY to employee #2.
1sy employee is not allowed to do this, since it falls into some kind of harassment.
Protocol and procedure dictates that if any employee has a complaint about another, they MUST report it to a supervisor, and ARE NOT allowed to directly address the employee in question about it.
Employee #2 has the right to not be bothered and/or harassed, even if it is about a complaint.

Only a MANAGER has the power to speak to that employee about the complaint, and discipline accordingly.

What is this called, and what (set of laws, or rights) does it fall under?