Under Manage Hudson/Configure System/"Security Realm" I've selected "Active Directory". Hudson is leveraging our organization's Active Directory for user authentication.
Under "Authorization" I use "Project-based Matrix Authorization Strategy".
If I log in as "william_leara", everything is fine. If I log in as "William_Leara", I am allowed to log in, but I am missing all permissions specific to me. (e.g. configure slave, configure job, start a build, etc.) It looks like I'm getting "Anonymous" permissions.
Active Directory is not case-sensitive, so I would expect either "william_leara" or "William_Leara" to work. But the permissions need to be consistent. Alternatively, if there were a technical reason you needed to enforce case-sensitivity, you should disallow "William_Leara" from logging in. It seems broken to me to allow the user to log in, but not grant him his permissions.