In the battle over books, who gets to decide what's age-appropriate at libraries?

Parents Against Bad Books co-founder Carolyn Harrison (center) talks with people last month outside the public library in Idaho Falls, Idaho, about what she considers obscene books on the shelves. (Kim Raff for NPR)

For months, Carolyn Harrison and a small band of activists have been setting up folding tables with an array of what they call "bad books" outside the public library in Idaho Falls, Idaho. As Harrison, co-founder of the group Parents Against Bad Books sees it, the best way to convince people that the library is stocking inappropriate books is to show them.

"These two books are in the library, if you don't believe it!" Harrison says to one passerby.