The one that comes to mind is U.S. v Olofson.
Olofson screwed up all right, but not with a trigger job.
The gun in question had a three-position selector as well as other parts and modifications that suggested it was intended to "malfunction" in exactly the manner that it did.
In addition, Olofson was or had been in the business of selling information on how to convert that particular firearm to full automatic.
Olofson also posted extensively on arfcom indicating that he intended to argue the case based on his claim that the feds had no jurisdiction in the case. He stated that defense had worked for him in federal court before. He had no intention, apparently, of trying to prove that the gun was simply exhibiting an unintentional malfunction.
It's possible he was railroaded over a screwed up trigger job, but, if so, it would be hard to find an innocent man who worked harder to make himself look guilty than Olofson did.