Rule Definition
Referencing down the inheritance tree is against Object-Oriented coding practices. It is a way of having two-way inheritance between class (or interface) and subclass (or subinterface). This is an indication of poor class (or interface) design and class (or interface) inheritance. Such practices increase the complexity of the application.

Remediation
Review the design of the Class hierarchy

Violation Code Sample

C# Sample:
    public class MySuperClass
    {
        public void aMethod() { MySubClass c = null; } // VIOLATION: Reference to a sub class
    }

    class MySubClass : MySuperClass
    {
        protected int m_subclassField = 0;
    }

CISQ rule: ASCRM-RLB-14.