It's tricky. The All Writs Act clearly must have some boundaries as to reasonableness and the due process of the defendant.
What Apple is being asked to do here isn't simply to unlock a phone. They're being asked to use their engineers, money, and expertise to build a tool to defeat the very encryption they developed.
It's not clear the All Writs Act enables the government to simply order a search warrant recipient to create new technology for them.
There is also a first amendment angle in that due to the previous crypto wars code is considered speech so the act of forcing a developer to write code could be considered compelled speech.
What Apple is being asked to do here isn't simply to unlock a phone. They're being asked to use their engineers, money, and expertise to build a tool to defeat the very encryption they developed.
It's not clear the All Writs Act enables the government to simply order a search warrant recipient to create new technology for them.