The doctrine of interposition is normally applied to lesser magistrates intervening against the wickedness of greater magistrates and so overturning their rule.
Three things here
1.) In these united States it is ipso facto an error to think of the FEDS as the greater Magistrates. The FEDS are not automatically the greater magistrates. As such if and when a state magistrate had to step in to contravene a decision from the Federal magistrate this would not be an example of interposition since often the state magistrate is the greater magistrate vis-a-vis the Federal magistrate.
2.) When it is the case that there are no lesser magistrates in the civil social realm to practice the doctrine of interposition that does not mean that there are no longer options. When there are no lesser magistrates to embrace and practice interposition then interposition would seem to require a magistrate from a different jurisdiction finally stepping up to adhere and practice this doctrine. This means if there are no lesser magistrates in the civil-social realm to stop the evil of wicked magistrates — perhaps because of fear or timidity — then interposition can still take place as magistrates from other jurisdictions are now responsible to place themselves as God’s spokesman between the wicked magistrates and the people.
These other magistrates from other jurisdictional realms that must step forward to practice interposition where there are no lesser magistrates to practice interposition in the civil social realm are the Clergy and Elders if any exist. If no lesser magistrate from the civil-social realm will interposit themselves between the people and the greater magistrates then the Clergy and Elders must practice the doctrine of interposition as magistrates coming from a different jurisdictional realm to straighten out a jurisdictional realm that had gone completely rebellious against God and His law-order. Clergy and Elders must rebel against the rule of the greater and lesser magistrates in order to be faithful to God and His law-word.
I believe that this is the point we are coming to and there may be little hope even in this because so few clergy members are willing to step up and resist wickedness from wicked magistrates.
We see this kind of action in the OT with Elijah as a member of the Prophet class practicing interposition against Jezebel and Ahab. As such, there is precedent for what I have laid out above.
3.) Following John Knox, I believe that if neither the lesser magistrates in the civil-social realm will not interposit themselves against greater magistrates for God’s glory and for the protection of the people and if clergy and Elders will not, in turn, interposit themselves against wicked greater and lesser magistrates then the responsibility for interposition falls to the jurisdictional realm of the family and faithful fathers must step up to practice interposition.