*sigh* The actual rationale (from the Chicago Tribune) is even stupider than I could think of.

Senate Republican leaders did not go as far as their House counterparts in ordering Schiavo and her husband to testify. Instead, they issued invitations to appear on March 28, the Monday after Easter.

Those invitations carried with them the protection that all congressional witnesses receive under a law that prevents tampering with or threatening them.

So Congress is now claiming the power to compel life-sustaining medical treatment whenever they feel like it? Sucks to be Christian Scientist....