What constitutes obscenity? On what grounds could and should books be banned - or on what grounds could and should purportedly "obscene" books be defended? The New Yorker's Louis Menand has detailed the twentieth-century war against censorship waged by various publishing mavericks in defence of such infamous works as D H Lawrence's Lady Chatterley's Lover and Henry Miller's Tropic Of Cancer. Needless to say, the pioneers who did the dirty work (albeit not necessarily for the most honourable motives) weren't those who ended up profiting from the liberalisation of the regulations surrounding the publishing industry.
(Thanks to Terry for the link.)