The proposed legislation would add more court reviews of NSA activities, require additional reporting by the agency and shorten the expiration time for authorization of some data collection.
"The companies have a big voice and Congress will listen to that voice," Fakhoury said.
How many lawmakers listen in Congress will determine whether Leahy's proposals get approved. Dianne Feinstein, chairwoman of the Senate Intelligence Committee, has introduced a competing bill more focused on transparency than restricting data gathering.
Civil rights advocates have said Feinstein's proposal fails to go far enough to curtail the NSA.
"If Feinstein's legislation were to pass, it would show the world that Congress no longer respects its citizens' fundamental privacy rights," Nicole Ozer, technology and civil liberties policy director at the American Civil Liberties Union of Northern California, said in a op-ed piece that appeared in the San Jose Mercury News.
The companies' letter is consistent with many of the Internet giant's efforts to appease customer concerns through better data encryption. For example, Microsoft reported last week that it would expand encryption across its services and let customers review more source code for back doors that could be exploited by the NSA.
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