Relevant part of the article:
>In a secret court in Washington, Yahoo’s top lawyers made their case. The government had sought help in spying on certain foreign users, without a warrant, and Yahoo had refused, saying the broad requests were unconstitutional. Related
>The judges disagreed. That left Yahoo two choices: Hand over the data or break the law.
>So Yahoo became part of the National Security Agency’s secret Internet surveillance program, Prism, according to leaked N.S.A. documents, as did seven other Internet companies.
From the court order:
"After a careful calibration of this balance and consideration of the myriad of legal issues presented, we affirm the lower court's determinations that the directives at issue are lawful and that compliance with them is obligatory."
Seems to me that tptacek is supporting my hypothesis