I think that the government expert is a man, who is very smart. And the defense has a woman, who is saying stuff, not using big words...that might make more sense to a layperson who does not have a lot of advanced computer knowledge.
It only takes one juror for a mistrial.
Don't overestimate the intelligence of the average person in the United States. The average literacy level is 7th grade.
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My experience with technology stuff is that folks like to hear the complicated words AND they like someone to translate it for them. They'll believe the complicated and feel reassured by the plain English.
I set up a team like this back in the day. I was the "translator". The other person—a guy—was my systems engineer. He was very techie, I could sound like one of the customers. The team was extremely successful. But my experience was, they always believed my partner; he had more credibility. But by "translating", I enhanced it.
Also, from my experience in that context: they'll believe a guy lots faster than a woman. The prosecution had mostly guys on the stand? Except for the one witness? There may be something about the jury we don't know, like a meaningful sexist bias. (This could be why they didn't call Jill?)
Defense should have brought in a GUY to be the tech expert witness IMO.
Regular folks are just as likely to not understand the significance of a router. Sure, they might have one at home, but they might not have programmed it, and they might be quite certain no one can access it but themselves in their home. So, the defense expert can babble on, but without doing a heck of a lot of instruction on how a router can theoretically be accessed from another place, and why a business would do that, and the settings that might be involved that most businesses don't use—why would a used car dealership allow remote access to a router?— I wouldn't jump to the assumption that the jury will believe it was. All this reinforced by their home experience.
I'm not sure what good it would have done for the prosecution to have a physical router. The only thing that matters is the settings. And they might have the settings. The wifi company has the settings? The wifi company would presumably know if there were hotspots on.
But really, on balance, I don't think the average person thinks their own router can be reached from outside the house, and IMO they'd extend that notion to a small business.
And if they've ever tried to log on to McDonalds' wifi from out in the parking lot (doesn't work), they'd get reinforcement for the idea that the router is for inside at a business.
Plus, the prosecution's tech-spertise was all LE? This will have weight IMO. And their woman tech was LE, too? Authority....
What is defense trying to argue, anyway? Someone else magically put CSAM on Josh's computer? What for?