Last Friday, Special Counsel Robert Mueller submitted his long-awaited report to Attorney General William Barr.  But so far, all Congress and the public have seen is a short memorandum providing Barr’s take on it.

Members of Congress have promised to exercise Congress’s subpoena power to get the full report, if necessary, and they should.  After all, Barr’s summary raises more questions than it answers, and Congress and the public deserve to know more about what Mueller discovered.  But Congress also has another avenue for pursuing information related to this investigation: the federal grand jury that has been working with Mueller’s team for the past two years.

This grand jury has likely seen a treasure trove of information associated with Mueller’s investigation.  As Barr’s memorandum notes, Mueller’s team “issued more than 2,800 subpoenas, executed nearly 500 search warrants, obtained more than 230 orders for communication records, issued almost 50 orders authorizing use of pen registers, made 13 requests to foreign governments for evidence, and interviewed approximately 500 witnesses.”  Some of that information has likely been presented to the grand jury to support the many indictments the grand jury has approved.

Given this, Congress could ask the district court judge to release certain grand jury transcripts and other information it knows the grand jury has seen over the course of the investigation.  Such a request would be consistent with federal law.  Under Federal Rule of Criminal Procedure 6(e), while grand jurors and government attorneys are prohibited from disclosing grand jury materials, the district court judge overseeing the grand jury may release those materials in a variety of circumstances, including “preliminarily to or in connection with a judicial proceeding.”

Moreover, numerous courts have held that district courts have inherent authority—outside of Rule 6(e)—to release grand jury materials when doing so is in the public interest.  As one put it, “it is certain that a court’s power to order disclosure of grand jury records is not strictly confined to instances spelled out in the rule.”  (In fact, the D.C. Circuit is currently considering this issue in a case called McKeever v. Barr.)

There is strong historical precedent for the idea that grand jury materials should be released when they would facilitate an ongoing congressional investigation into the President.  In 1972, the grand jury investigating the Watergate scandal wrote a report and recommended that the report be submitted to the House Judiciary Committee for its consideration as part of impeachment proceedings against President Nixon.  The district court approved this request, emphasizing that it was “deal[ing] in a matter of the most critical moment to the nation, an impeachment investigation involving the President,” and that “[i]t would be difficult to conceive of a more compelling need than that of this country for an unswervingly fair inquiry based on all the pertinent information.”  Thus, although the court did not approve a public disclosure of the grand jury report, it held that there was “ample basis” for disclosing the report to the House Judiciary Committee.

To be sure, there is no formal impeachment investigation here, but the House has left no doubt that its committees will be picking up where the Mueller investigation left off.  And materials from the Mueller grand jury could provide Congress with a roadmap, or other useful information, as it carries out that critically important investigation.

Notably, Chief Judge Beryl Howell—the judge who impaneled the Mueller grand jury and who would make any decision about whether to disclose any Mueller grand jury materials—recently recognized that “a district court retains an inherent authority to unseal and disclose grand jury material not otherwise falling within the enumerated exceptions to Rule 6(e)” as part of its “supervisory authority over grand juries” in the context of deciding to unseal some materials associated with Ken Starr’s investigation into President Clinton.

In sum, Congress could request that Chief Judge Howell provide it with materials from the Mueller grand jury.  Requesting this grand jury information could be particularly important here because Barr’s letter implies that he views some of the material in Mueller’s report as covered by the Rule 6(e) secrecy provisions, and he might refuse to disclose portions of the report on that basis.

Of course, Congress could not require the district court judge to release grand jury materials; the district court judge has discretion to determine whether disclosure is warranted in each particular case.  (Indeed, in the Starr case, Chief Judge Howell unsealed some, but not all, of the requested materials.)  But that would be a call for the district court judge—and not President Trump’s Attorney General—to make.

In short, Congress needs to know more about the underlying facts that formed the basis of Mueller’s conclusion.  And grand jury records may be another way to get that critical information.