Did the Mueller team violate Brady and Flynn orders?

Now back to Brady and the prior orders of Judge Sullivan (who is have practiced in front of for many years).

At least as early as February 2018, federal prosecutor Brandon Van Grack (who was one of Mueller’s staff) was under order in the Flynn case to produce all evidence in the government’s possession “that is favorable to defendant and material either to defendant’s guilt or punishment.” There was also an obligation to turn over all favorable defense evidence, including impeachment evidence for witnesses even if the government believes the evidence “not to be material.”

In 2019, Van Grack repeated the denial that there was “any information that would be favorable and material to [Flynn] at sentencing.”

So we now know that the Justice Department was withholding a January 4, 2017 document entitled “Closing Communication” from the FBI Washington Field Office. That document declared that an investigation “did not yield any information on which to predicate further investigative efforts.” In what universe would that not be :favorable to defendant and material either to defendant’s guilt or punishment”? Moreover, it would be key impeachment evidence in examining investigators or other witnesses. As a criminal defense attorney for 30 years, I would have viewed the material above as a windfall of evidence favorable to my client.