How to use reflection to determine if a class is internal?

This is a classic issue. From MSDN:

The C# keywords protected and internal have no meaning in IL and are not used in the Reflection APIs. The corresponding terms in IL are Family and Assembly. To identify an internal method using Reflection, use the IsAssembly property. To identify a protected internal method, use the IsFamilyOrAssembly.

Reflection does not expose a way on Type check if it is internal, protected or protected internal.