The figure of Ataturk and the Turkish national identitiy are immune to any pejorative terms de jure. The rest is forbidden de facto, that is, if you are strong enough, you can try to silence the opposition with lawsuits for hate speech, public insulting, and treason, and laws for detention can be abused to keep them at lenght in prison. See the recent Can Dundar-Ekrem Gul case for treason and publication of statal secrets.

So it's mostly an abuse of the law via installed judges and misuse of the constitution. The parliamenters are immune to lawsuits during their duty, so it's easier for them to act so.