It's not "unprecedented."
Let's all remember that Caspar Weinberger was indicted just four days before the George H. W. Bush v Bill Clinton election, so election-changing indictments have been done to Republicans.
In Weinberger's case, it greatly benefitted the rise of Bill Clinton, so it's the height of hypocrisy to complain about it now.
-PJ
What is “unprecedented” is such an action to damage a Democrat prior to an election. That is the unforgivable thing. Using it to take down a Republican is, well, de rigueur as the Republicans are wholly illegitimate and should not even be involved in the political process.