It is called the Rare and Restricted Room and it houses some of the State Library's most valuable publications, including an 1848 edition of John Gould's Birds of Australia.

On a shelf somewhere within that room is the library's smallest "collection" – a group of just 11 books, all of which are banned from public access.

"We've reduced the collection to books that are actually illegal to provide to members of the public," said Joan Bruce, Queensland literature co-ordinator at the State Library of Queensland.

"The Libraries Act says we have to keep at least one copy of everything that's published in Queensland, so that's the reason why most of it is kept."

While books in the past were often banned for being "obscene" and "filthy", such as Philip Roth's Portnoy's Complaint or the romance comic Love Illustrated, most of the books in the banned section are there for legal reasons.

Ms Bruce said a few of the banned books were ones the library purchased because they were thought to be "useful publications", but had to be withdrawn from public shelves after legal proceedings were started.

One such book is Cannabis by Jonathon Green, a book on the history of cannabis use.

"Some Rockhampton magistrates court banned it so it had to be withdrawn from our shelf for that reason," Ms Bruce said.

"It's illegal for us to provide it to the public, but that might change, who knows?"

And that's one of the reasons why the library keeps books it isn't allowed to lend to the public - eventually, some of the bans are removed.

"I actually think the more interesting ones are the ones that were banned in the past," Ms Bruce said.

"The first edition of A History of Queensland volume two was restricted because of a defamation suit by Joh Bjelke-Petersen, and he died years ago so defamation is no longer an issue."

The book sat in the banned book section until the librarians realised it could probably be safely released.

"Several of us turned around at the same time and went 'wait a minute, what's going on here, we better have a look at that', and that was released a bit over a year ago," she said.

"So there are some that if it's a defamation suit, eventually they will be available."

While the public are not able to access these banned books at all through the library, they can read some of the other publications in the Rare and Restricted Room.

"That material has to be called out by the member of the public and used in the level four reading room, under supervision by a staff member," Ms Bruce said.

"They're not actually going to be hanging over your shoulder, but you sit close by the desk where they are."

That's because some of the items in that collection are not only rare, but incredibly fragile.

One of the items is a silk-covered album of Chinese export trade botanical paintings, painted on delicate pith paper around 1840.

The paper is so delicate, according to the catalogue notes, "albums are seldom found without tears to some pages".