Apple CEO Tim Cook on Tuesday evening said the US government's legal position on encryption backdoors was setting "a dangerous precedent.” That’s because, just a few hours prior, a federal judge agreed with the US Justice Department that a 1789 law compelled Apple to alter an iPhone's firmware that would allow the authorities to use a brute-force attack on an iPhone owned by one of the San Bernardino shooters.
Cook said Apple will fight the Riverside, California magistrate judge's orders, calling it an "unprecedented use of the All Writs Act of 1789 to justify an expansion of its authority." Depending on where you line up in the cryptowars debate, Cook's characterization of the government's stance may or may not be true. But what is undeniable is that the act has certainly been used to expand the government's surveillance reach. Whether it ultimately will in the iPhone case is an open question likely to be resolved by the Supreme Court.
While the All Writs Act is not used every day, the act has been successfully invoked by the government to compel telephone companies to install wiretaps, for phone companies to hand over call records, to obtain CCTV footage, handwriting exemplars, and DNA samples. It's even been cited to force a defendant to cough up his computer password.