You can't build a backdoor that only the good guys can walk through.
"Encryption protects against cybercriminals, industrial competitors, the Chinese secret police and the FBI. You're either vulnerable to eavesdropping by any of them, or you're secure from eavesdropping from all of them[...] FBI Director James Comey claimed that Apple's move allows people to "place themselves beyond the law" and also invoked that now overworked "child kidnapper." John J. Escalante, chief of detectives for the Chicago police department now holds the title of most hysterical: "Apple will become the phone of choice for the pedophile. It's all bluster. Of the 3,576 major offenses for which warrants were granted for communications interception in 2013, exactly one involved kidnapping. And, more importantly, there's no evidence that encryption hampers criminal investigations in any serious way. In 2013, encryption foiled the police nine times, up from four in 2012Â -- and the investigations proceeded in some other way. This is why the FBI's scare stories tend to wither after public scrutiny."