I had gotten a ticket for obstructing the intersection (the "anti-congestion" law in California that sought to limit gridlock by making it illegal to enter an intersection that you couldn't exit before the other light changed). I was fighting it and wanted to find other cases that had been decided on this law[1]. The only way to do that was to go to the public library and look through their published volumes of decisions and cases. So I thought here is a really useful thing Google could do, it isn't even a hard problem, collect the decisions that the courts publish anyway, and just connect the ones that are about the same part of the code. Match a number, match a date. And very useful to people who are fighting cases. It saved me some time and money [2]. But the idea never made it past the discussion stage because, as I was counseled, doing that would take on "powerful interests" who would really fight back hard and Google didn't want to draw that level of scrutiny. It wasn't until Carl Malamude started attacking this problem in earnest[3] that it became clear to me what it means to take away a revenue stream from lawyers.
[1] And learned this is called 'Sheparding' based on finding citations -- https://en.wikipedia.org/wiki/Shepard's_Citations
[2] turns out there had been no case law on this particular law and lots of dismissals so I just entered a plea of not guilty at the clerk, and the court informed me a week before my trial date that the prosecution had declined to prosecute.
[3] https://www.techdirt.com/articles/20150726/23080731763/even-...