I can’t recommend strongly enough that you take the time to read the entirety of APPLE INC.’S REPLY TO GOVERNMENT’S OPPOSITION TO APPLE INC.’S MOTION TO VACATE ORDER COMPELLING APPLE INC. TO ASSIST AGENTS IN SEARCH. Some gems below:

The government attempts to rewrite history by portraying the [All Writs] Act as an all-powerful magic wand rather than the limited procedural tool it is. […] Thus, according to the government, short of kidnapping or breaking an express law, the courts can order private parties to do virtually anything the Justice Department and FBI can dream up. The Founders would be appalled.
This case arises in a difficult context after a terrible tragedy. But it is in just such highly-charged and emotional cases that the courts must zealously guard civil liberties and the rule of law and reject government overreaching.
Indeed, it is telling that the government fails even to confront the hypotheticals posed to it (e.g., compelling a pharmaceutical company to manufacture lethal injection drugs, Dkt. 16 (“Mot.”) at 26), or explain how there is any conceivable daylight between GovtOS today, and LocationTrackingOS and EavesdropOS tomorrow.
The government also implicitly threatens that if Apple does not acquiesce, the government will seek to compel Apple to turn over its source code and private electronic signature. Opp. 22 n.9. The catastrophic security implications of that threat only highlight the government’s fundamental misunderstanding or reckless disregard of the technology at issue and the security risks implicated by its suggestion.

The government’s position has sweeping implications. Under the government’s view, the state could force an artist to paint a poster, a singer to perform a song, or an author to write a book, so long as its purpose was to achieve some permissible end, whether increasing military enrollment or promoting public health. […] The First Amendment does not permit such a wholesale derogation of Americans’ right not to speak.

Again―Read the whole thing here: APPLE INC.’S REPLY TO GOVERNMENT’S OPPOSITION TO APPLE INC.’S MOTION TO VACATE ORDER COMPELLING APPLE INC. TO ASSIST AGENTS IN SEARCH