Anyone with perms can ban eachother

[SaladsBowl]

So, as it currently stands, all groups that hold the permission to ban can ban eachother. I would like to see a feature implemented where a group of higher priority cannot be banned by that of a lower priority, and those within the same group cannot target eachother.
For example, on my server we have a Server Manager group that has more perms than our Admin group, therefore outranking them. With the current system, Admins can not only ban each-other, but can also ban Server Managers.