On thing that I especially like about this book - In Defence of Freedom of Speech by Chris Berg - is the way it recounts the history of freedom of speech as a concept in Western political thought. In doing so, it goes back to the trial of Socrates and even earlier.
I'm fascinated by the history of ideas, so I love a good book that tries to place our modern philosophical and political concepts in historical perspective. If this is done well, it is an excellent way of digging into what has really bugged people in a certain area, and how that has contributed to the concepts that we have today. That's not to say that we now ought to be bound by whatever it was that concerned people in the past, but the record of what did concern them provides clues as to what modern people may have in mind with a particular concept, why many of our concepts defy coherent explication (perhaps because not-entirely-consistent meanings are getting forced into one package), and what sorts of things may be bugging people even now - whether or not they are clearly articulated.
So, I'm always willing to read narratives involving the history of ideas.
(And I can't resist mentioning that Freedom of Religion and the Secular State also does a fair bit of this (in dealing with such ideas as religious tolerance, freedom of religion, secularism, etc.).)
Berg digs pretty deeply into the ancient conceptions of freedom of speech - those of Greece and Rome - so much so, in fact, that I have to take his word for some of this. I'd have to do a fair bit of checking to be independently confident that he's right when, for example, he discusses the classical Athenian conception as predominantly about a social responsibility to speak your mind frankly, clearly, and directly to your fellow citizens. It was not seen so much as an individual right of self-expression.
If this is correct, it helps explain why the Athenians' conception of what we'd now call freedom of speech did little to help Socrates.
While it is difficult to get much of a handle on the historical Socrates, given the literary, tendentious, and somewhat conflicting nature of our sources, it is at least plausible that his fellows disliked him partly because he did not speak frankly, clearly, and directly, but engaged, instead, in a kind of philosophical discourse that was calculated to lead people into contradiction and confusion - thus exposing the vagueness and incoherence in their concepts. I'd like to read some more about this (and Berg offers some starting points in the scholarly literature).
In any event, In Defence of Freedom of Speech does an enjoyable job of examining different conceptions of this freedom through the ages, different justifications for it, and different concerns that it has addressed. In the end, Berg justifies freedom of speech on strongly libertarian and individualistic grounds - as something needed for our moral autonomy - and is lukewarm about other justifications, such as its importance in the search for truth or for the functioning of democratic processes. This leads him to a position considerably more absolute than my own (as I mentioned yesterday).
But that is actually rather refreshing! It's nice to read a truly forthright defence of our freedom to express ourselves, when so many contemporary thinkers seem to think this freedom is rather unimportant and should be trumped by many other considerations.