Google responds to legal requests for information. The whole PRISM scandal was indicating that the NSA had some kind of direct link into the databases themselves. This assertion is what Google denied, and still denies.

There's been a bit of a wandering definition for PRISM, from "they have NSA software with root access to all machines!" to "they receive LEO requests for information, which they review, and sometimes fulfill." The former is untrue, and the latter is true.