Why should a professor get more 1st amendment protection than adeputy district attorney? In Garcetti v. Ceballos, 547 U.S. 410 (2006), the US Supreme Court (5-4) held that when public employees make statements pursuant to their official duties, they are not speaking as citizens for 1st amendment purposes, and the constitution does not insulate their communications from employer discipline. However, the Court expressly did not decide whether this rule applies to speech involving scholarship or teaching.
The 9th Circuit has now held that Garcetti does not apply to teaching and writing on academic matters by teachers employed by the state, and that the proper framework is the one laid out in Pickering v. Board of Education, 391 U.S. 563 (1968). Demers v. Austin (9th Cir 09/03/2013). [Same result in the 4th Circuit.]
Professor David Demers distributed a pamphlet plus a draft of parts of a book he was working on. Later he claimed that officials of his employer -- a state-owned university -- retaliated against him because of the content of the pamphlet and book draft. Demers sued the school officials claiming 1st amendment retaliation. The federal district court gave judgment to the defendants on the basis of Garcetti; the 9th Circuit reversed.
As much as I value the policy of academic freedom (the full definition of which is admittedly elusive), I don't see how the constitutionalization of this policy can be played out in a principled way. Many (perhaps the overwhelming majority) of personnel decisions in academia are made on the basis of the content of academic writings. I prefer the judgments of the academics (with all their probable errors) over the judgments of the courts and juries (who know little about the merits of academic writing).