The version of the Mueller report provided to select members of Congress is almost entirely unredacted, according to the Justice Department, and the portions that are redacted are confidential by law.

The Justice Department made this clear in a little-noticed letter last week to Democratic New York Rep. Jerry Nadler, who chairs the House Judiciary Committee. Nadler’s demand to see the entire Mueller report has provoked a standoff with the White House, which has resulted in Trump asserting executive privilege over information that is actually illegal to release, even to Congress.

Only 1.5% of the version of the Mueller report made available to Nadler and other congressional leaders is redacted, the DOJ said in the letter. Those portions are redacted only for grand jury information, which is prohibited from release by law.

House Democrats voted to hold Attorney General William Barr in contempt of Congress on Wednesday over his refusal to release the entire report, as well as underlying materials. Nadler says they need the information in order to fully understand Mueller’s findings on whether Trump obstructed justice. But according to the DOJ letter, just .01% of the redacted portions of the report already available to Congress are in the portion on obstruction of justice. (RELATED: White House Slams Mueller Report In Letter To Attorney General Barr)

The DOJ reiterated the fact that revealing the remaining redacted parts of the report would be illegal, in a Wednesday letter to Nadler that informed him that Trump will assert executive privilege over the information. “As we have repeatedly explained, the Attorney General could not comply with your subpoena in its current form without violating the law, court rules, and court orders, and without threatening the independence of the Department of Justice’s prosecutorial functions,” the letter said.

Government attorneys are prohibited by law from disclosing any matter related to grand jury proceedings, and people external to the proceedings are prohibited from obtaining any information that would reveal what took place, according to a Congressional Research Service report. This applies even after the proceedings are concluded, and even when the information is pursued for otherwise legitimate legal reasons.

The secrecy is intended to foster an environment in which witnesses feel free to speak and make assertions, but also to protect the accused who are not ultimately indicted by the jury from damage to their reputation and other expenses that would result from disclosure. Total secrecy has been the practice since the 17th century.

The CRS report notes that a few limited exceptions have been carved out in the courts, and that some courts have determined they would apply to information related to impeachment proceedings in Congress, but “there is authority to the contrary.”

Nadler said Wednesday he doesn’t believe the White House will follow through on the assertion of executive privilege, and said the idea that the authority would apply in this case is without legal merit. The White House said Wednesday none of the Democrats have read the version of the report that is almost entirely unredacted.

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