[Lurking Libertarian]

And congresspeople can defame at will, from the well of the their chambers.

That part is in the Constitution (Article I, section 6: "for any Speech or Debate in either House, they shall not be questioned in any other Place").

[Cboldt]

Indeed it is. I thought it was an interesting but tangential and irrelevant point to this suit. The wrongful death part will be tossed, but Hillary will have to pay some money to get a good defense for the defmation. The judge will toss it. No reasonable judge would find her liable for anything.