I was surprised to find the Eleventh Circuit en banc (10-3) held that a two-way video link -- such that people in the court can see and hear the witness and the witness can see and hear the defendant and the defendant's lawyer -- to witnesses in Australia who refused to come to America for a trial violated the Confrontation Clause.
My initial reaction was that obviously a two-way video link would satisfy the Constitution (so long as there was some reasonable reason the witness could not come to the trial). "The Confrontation Clause commands that reliability be assessed in a particular manner: by testing in the crucible of cross-examination." Crawford
The Court has previously allowed a one-way video link for the testimony of an allegedly abused child. The Court said there is no an absolute right to a face-to-face meeting with the witnesses,
The Clause's central purpose, to ensure the reliability of the evidence against a defendant by subjecting it to rigorous testing in an adversary proceeding before the trier of fact, is served by the combined effects of the elements of confrontation: physical presence, oath, cross-examination, and observation of demeanor by the trier of fact. Although face-to-face confrontation forms the core of the Clause's values, it is not an indispensable element of the confrontation right.
I would argue that a video link is "face-to-face." You could argue that seeing a person in three dimensions assists in determining if they are telling the truth. I doubt the truth-detecting abilities of juries in any case, but I think Americans have more experience watching people lie on television than in their physical presence.
Ironically, the Eleventh Circuit held that because the prosecution could have used a pre-trial deposition, the video-link testimony was not "necessary." So, testimony made weeks before trial - when the trier of fact cannot observe witness demeanor - is okay, but a real-time video link is not. And, not only is a pre-trial deposition acceptable under the Confrontation Clause, but the fact that such testimony could be used means a video-link cannot be used. Odd.