For nearly a decade, Diana Ramirez hadn't been able to take a book home from the San Diego Public Library. Her borrowing privileges were suspended, she was told, because of a mere $10 in late fees, an amount that had grown to $30 over the years. Ramirez, who is now 23 and stays in Tijuana with her mother, attends an alternative education program in San Diego that helps students earn high school diplomas. To her, the debt she owed to the library system was an onerous sum. Even worse, it removed a critical resource from her life. "I felt disappointed...