Given all of the obstacles to bringing a successful prosecution, it's remarkable that DOJ has indicted those five former Blackwater guards for their roles in the Nisour Square massacre. But one thing in particular is going under-reported in the coverage: In the hours immediately after the shootings, the State Department, who contracted with Blackwater, gave legal immunity to all of the Blackwater guards who were at the scene of the alleged crime in return for their accounts of the incident.

As we've reported in the past, DOJ is going to have fun overcoming that hurdle, having to demonstrate that the evidence they gathered for the indictment and prosecution was not fruit of that poison tree.