You are missinformed due to your termology. NSA assets collecting the signals are outside of the US. Any assest that might be are tuned to international communications. They cannot intercept internal (texas to ohio type) communications. So the intecept of purely domestic comms is not impossible, it is highly improbable. Just because one end of the conversation is in the US does not define it as 'domestic'.
I should have backed up my previous post that some attorneys and judges support the president's authority to conduct the NSA program and so I looked quickly and just grabbed this:
John Schmidt, who served as an assistant attorney general during the Clinton administration, weighs in with a Chicago Tribune op-ed on the wiretapping kerfuffle: President Bush's post- Sept. 11, 2001, authorization to the National Security Agency to carry out electronic surveillance into private phone calls and e-mails is consistent with court decisions and with the positions of the Justice Department under prior presidents
No, I'm not misinformed. What I stated is exactly what I've read. The program has monitored communications between two points within the US. They contend it was accidental.