Who says Barr can't turn anything over to congress? The DOJ certainly turned over top secret documents to Congress when the intent was to damage Hillary's political fortunes.
"WASHINGTON — The F.B.I. on Tuesday handed over to Congress documents related to its investigation of Hillary Clinton’s private email server after House Republicans pushed the bureau to surrender material it had gathered before it concluded last month that she should not face criminal charges.
The documents were believed to include notes from the F.B.I.’s 3½-hour interview with Mrs. Clinton in early July, the last step in a lengthy investigation into her email practices as secretary of state that continues to dog her run for president."
https://www.nytimes.com/2016/08/17/us/politics/fbi-gives-congress-documents-related-to-hillary-clinton-e-mail-inquiry.html
