Josh Bell of the American Civil Liberties Union tells Boing Boing,
We're currently fighting a FOIA lawsuit to get the entire Senate torture report released, as well as the official CIA response and the so-called Panetta Report. Last night, in response to Sen. Burr's recent request for the administration to return all copies of the report, we filed an emergency motion to stop such a return from happening.
Congressional records are not covered by the Freedom of Information Act (FOIA), so returning the report to the Senate could have the effect of thwarting the lawsuit and keeping the report secret forever–or at least as long as republicans are in control of the Intel Committee.
The motion lays it all out (esp. in the first two pages, including DOJ's response on the matter). Here it is [PDF].
One other thing to note is that the White House hasn't weighed in on Burr's request or said whether the it thinks the full report should be public.