Back in 1992, AT&T paid an expert witness to spend over 400 hours a**essing Berkeley’s version of Unix line by line, and what he returned with amounted to 186 lines of code, when Berkeley’s own release amounted to roughly 1.5 million lines. That was what was considered to be the meaningful code overlap at the center of a lawsuit that dragged on for 22 months and, arguably, decided which free Unix we all ended up running.