Don't Upset the Political Balance of Power, Please

Josh Marshall published a letter from one of his readers that made the following point:

And so it will be with TAM [The Abramoff Matter]. At some point TAM will become a potent enough matter to be profoundly political in nature and those involved in the legal system will have to withdraw. To do otherwise would be to improperly engage the legal system in a political contest and undermine the foundational premise of an independent judiciary.

In other words, once the prosecution of politicians threatens to alter the political balance of power, the prosecutions must cease. This makes no sense at all to me. It seems to suggest that politicians are above the law, particularly if those who are breaking the law are all from the same party. That's not the way I understand the Constitution. The "political witch hunt" excuse is already used too often. Let's not let fuzzy thinking like this gain any more ground.