BSD was not "clean-room", and AT&T sued when it was freely distributed, because they didn't believe that all AT&T code had been removed. https://en.wikipedia.o

BSD was not "clean-room", and AT&T sued when it was freely distributed, because they didn't believe that all AT&T code had been removed. https://en.wikipedia.org/wiki/USL_v._BSDi https://en.wikipedia.org/wiki/USL_v._BSDi