They could deal with escaped federal prisoners, smutty books crossing state lines.
他们可以处理逃亡的联邦囚犯、跨越州界的淫秽书籍。
英语百科
BookCrossing
(重定向自Book crossing)
BookCrossing (also BC, BCing or BXing) is defined as "the practice of leaving a book in a public place to be picked up and read by others, who then do likewise." The term is derived from bookcrossing.com, a free online book club which was founded to encourage the practice, aiming to "make the whole world a library."