The legal debate can be technical, but the easy answer—that presidents can obstruct justice—can be illustrated with a simple example. Consider two cases. In the first case, a defendant is found with heroin. Notwithstanding the overwhelming evidence of guilt, the prosecutor decides not to bring the case on the ground that doing so would be unjust on the particular facts.
Has the prosecutor obstructed justice? Clearly not. While the prosecutor could be said to be impeding the administration of justice, as defined by the statute, the decision is not corrupt. The decision was based on a view of the law, an allocation of scarce resources, and an independent judgment of what is just. The discretion granted all prosecutors embeds the power to determine the scope of justice.
But, what about a second case in which only one fact is changed: the defendant is the prosecutor’s son? In that case, the decision to not bring the case now looks more like favoritism or self interest than an independent assessment about justice. It violates the rule of law—the notion that the law should apply equally to everyone.
Read more at Fortune