Judge Tallman begins this opinion with the line: "The United States Constitution and federal law require that crimes be prosecuted where the offense was committed. This venue requirement, however, is more easily stated than applied."
The common reaction might be: "Yep. It's tough. Couldn't agree more."
But personally, I don't think the rule's very difficult to articulate. At all. Here's how I'd state the rule, at least as applied by contemprary federal courts:
"Venue exists in federal criminal cases virtually anywhere. Wherever there's even the most tenuous and/or government-manufactured contact with a crime, venue's proper there."
This case is a perfect example. The crime's entirely outside the Northern District of California. The defendant never steps foot there. Never does anything there. As far as we know, doesn't even know that the Northern District of California exists. The only thing that happens there is that a confidential informant who's working for the government -- who's working to destroy the conspiracy -- makes a telephone call from there to the defendant. The defendant didn't know the call was from the Northern District of California. Didn't know the CI was working for the government. Wouldn't have taken the call if he'd have known. Never benefitted, one iota, from the Northern District. Never purposefully (or otherwise) availed himself of the benefits of that forum.
In civil cases, we'd undeniably say that venue's improper. But the Ninth Circuit holds -- as pretty much every other circuit would surely hold as well -- that venue's nonetheless proper in that forum. Because even though proper venue's a constitutional requirement in only criminal (not civil) cases, as applied by the judiciary, that requirement's only really meaningful in the latter.
So you might have a variety of critiques about the federal venue rule in criminal cases. But that it's hard to apply isn't particularly one of them.