I'm actually quoting a quote:

By shifting the required certification from "the purpose" to "a significant purpose," . . . [the PATRIOT Act] necessarily reopens the seemingly settled question of FISA's constitutionality under the Fourth Amendment. First, to the extent that courts have recognized a foreign intelligence exception to the Fourth Amendment's warrant requirement, the question is whether that exception should apply where the gathering of foreign intelligence information is not the main purpose of the surveillance or search.

Apparently the government conceeded the point I raised earlier about the "primary purpose" of this investigation. Perhaps they did so intentionally to bring this question to litigation in a context where the specific outcome has limited relevance because the suspect is innocent.