Note that this is not the San Bernardino shooter case but just the drug case in NY.
Still, Judge Orenstein gave some extremely important arguments regarding the All Writs Act (AWA) that the government tries to use:
"The plain text of the statute thus confers on all federal courts the authority to issue orders where three requirements are satisfied:
1. issuance of the writ must be "in aid of" the issuing court's jurisdiction;
2. the type of writ requested must be "necessary or appropriate" to provide such aid to the issuing court's jurisdiction; and
3. the issuance of the writ must be "agreeable to the usages and principles of law.""
"As set forth below, I conclude that in the circumstances of this case, the government's application does not fully satisfy the statute's threshold requirements: although the government easily satisfies the statute's first two elements, the extraordinary relief it seeks cannot be considered "agreeable to the usages and principles of law." In arguing to the contrary, the government posits a reading of the latter phrase so expansive – and in particular, in such tension with the doctrine of separation of powers – as to cast doubt on the AWA's constitutionality if adopted."
In short, he recognized that "All Writs Act" can't mean "we can order anything we want to" to allow (in this case) DEA not following the laws that already exist (which specifically don't prescribe what DEA demands from Apple).