The best I can find is https://m.huffpost.com/us/entry/us_5cdd9f8fe4b01571365dc957 https://m.huffpost.com/us/entry/us_5cdd9f8fe4b01571365dc957 : “According to

The best I can find is https://m.huffpost.com/us/entry/us_5cdd9f8fe4b01571365dc957 https://m.huffpost.com/us/entry/us_5cdd9f8fe4b01571365dc957 : “According to [a spokesperson], Manning’s lawyers maintain that, since the grand jury is only an investigative tool and cannot be used by prosecutors to prepare for trials, the subpoena for Manning ‘represents an improper and impermissible use of the grand jury process.’” Apparently the judge disagreed with that argument, but I can’t find any reports on the judge’s reasoning.