Why did Mueller not file charges of campaign finance violations?

The indictment alleges facts that support charges of federal campaign finance law violations—such as the prohibition on foreign national contributions—but does not charge any such offenses. This is clearly not for want of evidence, since the indictment sets out in considerable detail the millions in foreign national spending to influence the 2016 election. Yet Bob Mueller omitted any direct charge for violations of the Federal Election Campaign Act.

Instead, the indictment builds the campaign finance issues into a conspiracy to defraud the United States—it alleges that the Russians conspired to obstruct the capacity of the Federal Election Commission (FEC) to enforce the law. The act of obstruction was a failure to report their illegal expenditures.

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Now, of course, those engaged in illegal campaign finance activity, such as spending from foreign national sources, won’t ever make an exception and comply with self-incriminating reporting requirements. And the irony of the premise–that the FEC would get the job done if given the needed facts–will not be lost on those who have observed the agency’s decline. But there is a theory, of course, behind the structure of the charges, and it might hold a clue to what comes next in the campaign finance phase of the case.

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Foreign nationals are plainly prohibited from spending in the manner detailed in the indictment. But how the law reaches American co-conspirators is less certain, and the special counsel’s theory of the case, pleading the campaign finance aspect of the case through conspiracy-to-defraud, may allow more securely for the prosecution of American actors.

  Just Security

It coincidentally makes me wonder which is the more severely punishable crime: conspiracy to defraud or campaign finance violation?

In other words, if Mueller’s case for campaign finance violations affected only Russians, there would be no obvious reason to exclude Federal Election Campaign Act violations from the indictment. [...] If, however, Mueller possesses evidence of Americans’ complicity in these violations, he may have decided on a different theory of the campaign finance case that more reliably sweeps in U.S. citizen misconduct.

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Any U.S. citizen who intentionally supported the Russian electoral intervention could be liable. Examples would include U.S. citizens engaged in conversations like those in Trump Tower in summer of 2016, or Don, Jr.’s communications with WikiLeaks about the timing of the release of stolen emails. The conspiracy to defraud the United States could also envelop any Americans who helped cover the Russians’ illegal electoral program by lying to federal authorities about the campaign’s Russian contacts.

Ya got me.  I'm going to have to wait for the final verdicts, and even then, I'll be poring over analyses and interpretations without a clear undersanding of just what the fuck happened.

My question at this point is, if Mueller has gotten this far down the line with conspiracy to defraud that he's able to file an indictment on 13 Russians, does that mean he's also got the information he needs to file indictments on any Americans involved?