When the FBI raids a lawyers office (like they did to Michael Cohen who is President Trump's personal lawyer) and they may have taken (either purposely or accidentally) documents and communications subject to Attorney–client privilege - how does the FBI and the Justice department put the Genie back in the bottle.
To determine if the communications are subject to Attorney–client privilege, somebody at Justice or the FBI will have to look at them. Once they look at them - they cannot un-see what they saw, they cannot unlearn what they learn from the documents.
Maybe Chinese walls - but I think the FBI and Dept of Justice have destroyed the trust the public once placed in them - to believe Chinese Walls would be sufficient.
How do we know this is not the Deep State trying to take down the duly elected President of the United States?