Does it shield the telcos from lawsuits resulting from unlawful domestic wiretapping? If so, that's a huge blow to the Fourth Amendment,
“Does it shield the telcos from lawsuits resulting from unlawful domestic wiretapping?”
First of all, it is not wiretapping, no matter how often the media calls it that.
Second, every call is foreign, no calls are domestic.
Third, the lines that are being intercepted are owned by the telecos, not the persons at each end, and the telecos have agreed to the intercepts, therefore, no warrant is needed. This does not effect the 4th amendment in the USA at all.