A TS/SCI clearance is the highest level of clearance granted, but having a TS/SCI clearance does not mean that you have the right to access all TS/SCI information. You must also demonstrate a "need-to-know" (in quotes because it's a term of art) that information.

Actually, this isn't quite right. There is a level of clearance higher than SCI. It's old name was SAP (special access program) but I think it's known as SAR (special access required) today. These are the "behind the green door" vault guys. Even a SCIF has to have special areas to handle those higher classifications.

I have a TS/SCI clearance with two compartments. That doesn't mean I'm cleared to any SCI info even within those compartments. I still have to have a "need to know." As for the other compartments, I'm not cleared for them at all, nor for SAP/SAR. This makes it a challenge to do my job sometimes but we adapt as best we can. Usually, it means meeting in a SCIF with someone who has the proper clearances and who decides what he can or can't tell me.