In Encounter at Farpoint, Picard has a conversation with Q:
Picard: We humans know our past, even when we're ashamed of it. I recognize this court system as the one that agreed with that line from Shakespeare: "Kill all the lawyers."
Q: Which was done.
Of course, the embedded quotation comes from Shakespeare's Henry VI, Part 2 (1591), and was likely a metaphorical expression about distaste for lawyers and litigation rather than a literal thirst for a profession-based genocide.
Despite this, we learn in the TNG era that the 21st century's experience with World War 3 and the Post-Atomic Horror was truly horrifying. The extent to which it really fit a traditional "post-apocalyptic" scenario was toned down slightly over the years, but never actually retconned. When I first saw the episode as a child, it made sense to me that something as nasty as the Horror could have included mass executions of practicing attorneys at the hands of disgusted citizens and that the reference was quite likely literal.
So, is Q being literal in that Earth-based lawyers were literally slaughtered en masse sometime between the 1980's and the 24th century or is he speaking more of a transition away from a litigation-based society and a corresponding reduction in the prestige of and necessity for lawyers on Earth? Are there any other episodes or secondary canon material that goes into more depth about specifically what happened here? In other words, were lawyers literally hanged, beheaded, drawn and quartered, strapped to lethal injection tables, disintegrated with plasma rifles, or otherwise dispatched with extreme prejudice or was it more that lawyers found themselves more and more out of work and pressured to transition to other careers like schoolteaching or dentistry?