Recently, a library worker got arrested in Nottingham after helping a student research an al-Qaeda training manual as part of his legitimate studies. Both he and the student he helped were detained for six days and threatened with deportation. They were eventually released without charges.
The library worker downloaded the manual from an official US government website, so it was a publicly available document.
As a consequence of this, the MLA (Museums, Libraries and Archives Council Consultation) updated its guidance and basically asked libraries to remove material that could be used by terrorists from their shelves. To me, this is a kind of censorship which is not compatible with the basic principles of democracy.
Luckily, many people in CILIP think along the same lines: Read the CILIP response here.