...and a solution that would fail to preserve the chain of evidence. If there's a black box at any point, e.g. Levison produces information and emails it to the investigating officers, the doctrine of "fruit of the poisoned tree" applies.
By that logic, doesn't Lavabit itself, or the entire SMTP system, serve as a black box? It's really not any different from the intercept features in telecommunications equipment.
If the government needs to preserve the chain of evidence by controlling every step of information flow in every criminal case, well clearly the government needs to ... sniff/control/spy-on the entire Internet. Whatda-ya-know...
It's a disruption of the chain of evidence, but my understanding is that "fruit of the poisonous tree" is something different: evidence gathered because of information the police should not have had access to.
