The Electronic Frontier Foundation has announced that Cloudflare is one of its clients [eff.org] in a lawsuit challenging the constitutionality of National Security Letters:
We're happy to be able to announce that Cloudflare is the second courageous client in EFF's long-running lawsuit challenging the government's unconstitutional national security letter (NSL) authority. Cloudflare, a provider of web performance and security services, just published its new transparency report announcing it has been fighting the NSL statute since 2013.
Like EFF's other client, CREDO, Cloudflare took a stand against the FBI's use of unilateral, perpetual NSL gag orders that resulted in a secret court battle stretching several years and counting. The litigation—seeking a ruling that the NSL power is unconstitutional—continues, but we're pleased that we can at long last publicly applaud Cloudflare for fighting on behalf of its customers. Now more than ever we need the technology community to stand with users in the courts. We hope others will follow Cloudflare's example.
16-16082 Notice to Court Concerning NSL [eff.org]