To be effective, the Department of Justice must be independent from partisan politics.

And, just as important, it must be perceived as independent.

Today’s reporting in The Daily Beast that the Department of Justice is reopening its investigation into Hillary Clinton’s use of a personal email server threatens to undermine that essential virtue.

Federal investigations are based on collection of evidence and legal analysis to determine whether a prosecution is in the best interests of justice. In the case of Hillary Clinton’s email server, FBI agents reviewed emails, interviewed witnesses, and reached the conclusion that no charges were appropriate.

In summer of 2016, then-FBI Director James Comey publicly announced that the FBI had concluded its investigation and was recommending against charging Clinton. Calling her conduct “extremely careless,” Comey nonetheless stated that no reasonable prosecutor would bring a case against Clinton for her conduct. Looking to prior cases, Comey said, “We cannot find a case that would support bringing criminal charges on these facts.” He noted that all previous prosecutions involved “some combination of clearly intentional and willful mishandling of classified information; or vast quantities of materials exposed in such a way as to support an inference of intentional misconduct; or indications of disloyalty to the United States; or efforts to obstruct justice. We do not see those things here.”

Comey reopened the investigation in October 2016 when seemingly new Clinton emails were found on a laptop computer, only to close it a few days later when the FBI reached the same conclusion as they had in July. That was the end of the investigation.

Until now.

During the campaign, then-candidate Donald Trump frequently blasted DOJ’s treatment of Clinton. In the past month, President Trump has renewed his criticism of the Justice Department regarding its treatment of “Crooked” Hillary, putting “Justice” in quotation marks in one tweet, and later demanding the “Deep State Justice Dept” finally act.

And now, it appears that DOJ is reopening the investigation. Renewing an investigation into the president’s political opponent just because he demands it is wrong and dangerous. The Department of Justice is not the president’s personal legal team, designed to lock up his rivals. DOJ has a long tradition of independence from the White House. Bowing to the wishes of the president to investigate his political enemies would undermine public confidence in the objectivity of DOJ’s charging decisions in this case and all others.

One legitimate reason to reopen an investigation would be the discovery of new evidence. Just as the FBI reopened the investigation in October upon finding new email messages on a laptop computer, reopening it again could be appropriate if some other new evidence has been discovered or new witness has been identified. But today’s report does not indicate that any new evidence has been discovered.

In the absence of newly discovered evidence, it would undermine the non-partisan nature of the Justice Department to reopen an investigation just because of a change in the party that is in charge of the executive branch. Reopening this case could set a dangerous precedent for future administrations to reconsider all charging decisions with which they disagree.

It may be, as some have speculated, that the new investigation is designed merely to appease Trump, and that officials know full well that no charges will emerge. Even that sort of charade would be an abuse of the awesome powers of the Department of Justice and a waste of resources that could be better spent on new cases. One would hope that DOJ’s leaders would have the backbone to reject such pressures rather than to pretend to accede to them.

At the end of his remarks announcing his recommendation in the Clinton case, Comey said, “What I can assure the American people is that this investigation was done competently, honestly, and independently. No outside influence of any kind was brought to bear.”

Will we be able to say the same about the new investigation?