It's pretty clear that the Obama administration and the Clinton campaign ginned up a phony dossier as a pretext to use the federal government intelligence apparatus to spy on the Trump campaign. It is also clear that the Obama administration was politically motivated to see that Hillary Clinton was not charged with any crimes as a result of the e-mail scandal. The evidence of both of these things is already in the public domain, in spite of the MSM downplaying the story. No one needs to subpoena anyone. All Jeff Sessions has to do is start perp-walking people, starting with Strzok and his honey bunny, based on the evidence we already have.
It makes me wonder what is really going on. Are they trying to horse-trade with Muelller: Hillary, Comey and Obama for Trump? I don't know, but it seems to me that using a phony dossier to get a wiretap clearance against your political enemy is pretty serious stuff in a republic as fragile as ours, and DOJ ought to be taking it more seriously.