Obama appointee Sally Yates was acting attorney general under President Trump for just 10 days — from Jan. 20, 2017 until Jan. 30, 2017 — but by any measure they were consequential days. Even now, two issues from Yates' brief tenure are still of interest to congressional investigators. One was the series of events that led Yates, in charge of the Justice Department, to reject the president's executive order temporarily suspending the admittance into the United States of people from some Muslim nations. The second is Yates' role in the FBI's questioning, apparently on dubious premises, the president's national security adviser, Michael Flynn, four days into the new administration — questioning that ultimately led to Flynn's guilty plea in the Trump-Russia investigation.

Both are matters of great public significance and interest — and on both, the Justice Department is refusing to allow the Senate Judiciary Committee access to documents from Yates' time in office.

On Feb. 23, 2017, Senate Judiciary Committee chairman Chuck Grassley wrote to Attorney General Jeff Sessions asking for "all emails to, from, copying, or blind-copying Ms. Yates from Jan. 20, 2017, through Jan. 31, 2017." Grassley also asked for all of Yates' other correspondence from that period, plus records of her calls and meetings.

The reason Grassley cited — his committee has direct oversight authority over the Justice Department — was that Yates' order to the Justice Department not to defend the president's executive order cost the administration precious time as it prepared to fight the inevitable legal challenges. The Department did not have its facts together when a federal judge in Washington state demanded them, setting the stage for the judge to issue a temporary restraining order.

"It looks like Ms. Yates' action may have substantially harmed the Justice Department's initial ability to defend the executive order," Grassley wrote. "It is important to determine the extent to which Ms. Yates' actions may have sabotaged the government's defense in that litigation."

"Even commentators who took issue with the executive order believed her directive to stop the entire Justice Department from defending the order in the middle of frenetic ongoing litigation was improper," Grassley added.

It is hard to imagine a matter of more public importance than that. But the executive order question was not the only issue involving Yates that fell under Grassley's oversight.

Also covered by the committee's request was any documentation of Yates' role in the Flynn case. A number of press accounts at the time the FBI interviewed Flynn cited an official "familiar with [Yates'] thinking" who said she was concerned that Flynn might have violated the Logan Act by talking to Russia's then-ambassador Sergey Kislyak during the presidential transition. Of course, many scholars view the Logan Act as a dead letter, and it is a fact that no one has ever been successfully prosecuted under the Logan Act at any time in its 200-year history. For Yates to use that particular law as a pretense for the FBI to interview Flynn was certainly a questionable decision — and a decision that Congress might reasonably want to review.

Grassley's request, covering all of Yates' communications, electronic and otherwise, would likely have given Congress some insight into Yates' thinking on the Logan Act and Flynn, as well as, of course, on the travel executive order. All were legitimate areas of congressional oversight. Yet the Justice Department turned the senator down flat.

"These records would implicate important executive branch confidentiality interests, including deliberations about the many sensitive law enforcement, national security, and policy matters that require an Attorney General's attention," Acting Assistant Attorney General Samuel Ramer wrote to Grassley in May of last year. Turning such records over to Congress would "substantially inhibit the robust exchange of views and advice" inside the Justice Department, Ramer said. It would also, he argued, "set an unacceptable precedent" of Congress mucking around in executive branch emails any time lawmakers "question an Attorney General's intent or motivation for a decision."

Of course, it had been done before. In November 2014, some of then-Attorney General Eric Holder's emails were turned over to Congress as part of its Fast & Furious investigation. And in December of last year the Justice Department turned over at least some of Yates' own emails in response to a Freedom of Information Act request by a private outside party, Judicial Watch. For example, on Jan. 30, 2017, Yates forwarded to someone — name redacted — an email from Andrew Weissmann, a top Justice Department official who later joined special counsel Robert Mueller's team. With the subject line, "I am so proud," Weissmann wrote 'And in awe. Thank you so much," for Yates' decision to block the president's executive order.

But now, the Justice Department refuses to hand over any of Yates' emails to the Senate committee with direct oversight authority. If the Department were serious about complying, it might ask for some limits on what has to be produced, and it's likely the Senate would have gone along, or at least negotiated about what should be turned over. But the Department just gave a flat no.

Grassley, unhappy, moved on. But he reminded the Justice Department that actions like Yates', on the executive order and other matters, have real consequences. "Having political appointees from a prior administration stay on during the early days of a new administration encourages stable transitions between administrations while new appointees are in the confirmation process," Grassley wrote. "When a holdover appointee uses that position to sabotage the incoming administration over policy differences, future administrations will be more likely to fire previous political appointees on day one, potentially leading to more dangerously rocky transitions. These stunts have consequences."