The 10 years that Dave Cullen spent researching and reporting on the 1999 shootings in Littleton, Colorado for his book "Columbine" were so draining that he experienced secondary PTSD. So on Feb. 14, 2018, when he heard about the shootings at Margery Stoneman Douglas High School in Parkland, Florida, he had no initial intention of writing about them. But in the nearly 20 years since the Columbine shootings changed our expectations about school safety, there had been a number of changes–including what the children directly impacted were able to do to change our national conversations about gun laws. In this episode of the Modern Law Library, Cullen speaks to the ABA Journal's Lee Rawles about his new book, “Parkland,” and how the Parkland students he met were able to create the impact they have in the year since the tragedy at their school.