Let iPhone users opt-in and you'll find far fewer proponents of backdoor encryption than will be reflected in Congress. I wouldn't be surprised if most in the LE and Intel communities didn't opt-in. Why? Perhaps because the USGOV has yet to prove they can keep their own data secure. The Office of Personnel Management hack, Clinton official emails on a private server, and many more instances have shaken the faith in USGOVs ability to be an effective steward. I'm in favor of master keys for the FBI after they prove to the public, in a transparent and accountable manner, that those keys can be kept unassailably secure from misappropriation or abuse.