I’m taking the liberty of quoting at length from an essay by Justin Florence on the Lawfare blog
(“On the Importance of Limiting White House-DOJ Contacts: It’s Not Just About Obstruction”).

Florence lays out why maintaining the wall between the White House and investigations conducted by the the Department of Justice is so important. It is based on a longer memo by a lawyers’ group, United to Protect Democracy, which traced the history of this important principle (“White House Communications With the DOJ and FBI”).

It’s an important issue, and the broader context is important to be aware of and keep in mind as daily events are unfolding.

First, a quite specific reason is that criminal laws prohibit interference in specific investigations. There has been much discussion lately of the contours of the federal obstruction of justice statute, 18 U.S.C. § 1505, a felony offense prohibiting certain “communication[s]” that “influence[], obstruct[], or impede[] or endeavor[] to influence, obstruct, or impede the due and proper administration of the law.” Contacts by the President or White House to the DOJ or FBI made with the intent to influence an investigation can not only give rise to criminal liability to the person who interferes, they can undermine the potential prosecution by allowing the defendant to raise claims of improper prosecution.

Second, restricting these contacts avoids the type of systemic corruption that is endemic in authoritarian governments. As Matt Yglesias described in a prescient essay earlier this year, when the political elite involve themselves in specific enforcement and regulatory actions, “Those who support the regime will receive favorable treatment from regulators, and those who oppose it will not.” As he notes, this type of interference can cut both ways. A call from a White House official to a federal prosecutor can ask that DOJ go easy on a friend of the administration who has worked for or donated to a campaign or who is a partner of the President’s business interests. Or, that same kind of call could suggest that it would be helpful to look into an enforcement action to brush back a journalist who has written a critical story of the President or a competitor to a business interest. As Yglesias writes, “This is how Vladimir Putin governs Russia, and how the Mubarak/Sisi regime rules Egypt.” It is not how America should function.

Third, limiting these contacts furthers several constitutional principles. The Constitution prohibits “bills of attainder,” and while that prohibition focuses on Congress, it stands for the more overarching point that specific people or groups should not be singled out for punishment. In addition, the Fifth Amendment’s Due Process Clause demands that our government follow standardized procedures before denying people of their liberty or property. The Equal Protection Clause requires that all people be treated equally under the laws. And finally, Article II’s command that the President “take care that the laws be faithfully executed” suggests a good faith requirement on the executive power. Each of these constitutional principles, in its own way, calls for the fair and impartial exercise of the Executive’s law enforcement authority. A White House that uses its enforcement power for political purposes—targeting specific individuals, ignoring standard law enforcement procedures, or treating similarly situated people unequally—fails to live up to these constitutional principles.

And this leads to the fourth and most fundamental point. The basic notion of the rule of law, and public confidence in the rule of law, requires its even-handed application. The DOJ and White House memos on contacts reference this concern. The DOJ memo currently in place begins, “The rule of law depends upon the evenhanded administration of Justice,” and continues that “in order to promote the rule of law” it is establishing guidelines to govern all communications between representatives of the Department, on the one hand, and representatives of the White House and Congress, on the other.” As we wrote when we asked the DOJ Inspector General to investigate whether the White House was violating these policies with respect to a specific enforcement matter, “The American people depend on the Department to enforce our federal laws equally as to all parties, regardless of those parties’ size, influence, or political connections.”