The Ministry of Justice tried to control the mass media to suppress their outrageous behaviors such as intruding on people's privacy and providing biased information. The "Media Improvement" bill secretly passed the House of Representatives while people were distracted by other big political scandal. Some congressmen were worried about the bill's excessive power and they decided to reinforce the authority of the library to counteract the "Media Improvement Committee" censorship. The Ministry of Justice cannot control the library because it belong to the local administration and is independent of the central government. The Media Improvement Forces provided arms to some extremists who support the censorship and let them attack the Hino Library. After this "Nightmare of Hino Library", Inamine founded the Library Forces with heavy arms to protect books from the attack.
It's a state's rights and freedom of speech argument all rolled into one. It's a great plot but the anime has so far not done the greatest job at explaining it.