Despite the other negative comments, I actually find this a vicarious account of the judicial system - a poignant reminder that behind any democratic system lies humans.
Friendly note: I think you want some word other than “vicarious”, which doesn’t make sense in context, the way the sentence is constructed. (I’m not precisely sure what you were trying to say, so I won’t suggest alternate words.)
Pretty sure this is a first-hand account. The author experienced the judicial system directly, as a juror. Then he wrote this first-hand account. If you told someone else about it, that would be second-hand.
The way he used the word “vicarious” is not idiomatically correct usage.
I don’t want to put words in his mouth, but I think he might have been trying to say that the author’s description was so vivid that he could vicariously experience the jury process through reading it.
In fengwick3's comment, "vicarious" modifies "account". Assuming "account" refers to the linked article, then it's first-hand, and not vicarious. fengwick3's (or your or my) experience of the judicial system through the linked article might be vicarious, but the article itself wasn't.
In a lot of the world, justice decisions are made by professional judges who have a lot of literature (laws, other decisions, and interpretation by higher courts) to guide their decisions. Which has the upside of more informed decisions (in France, it's interesting to see that professional judges seem more harsh than public jury tho.)