More than 2,000 police and fire departments have partnerships with Amazon to use surveillance video from its Ring security cameras. This week, the company changed the way law enforcement can access that video. Now, departments will have to post public requests on Amazon’s Neighbors app and include some details about the relevant investigation. Police used to be able to directly email users without making the request public. Marketplace’s Amy Scott speaks with Andrew Guthrie Ferguson, a law professor at American University and author of the book “The Rise of Big Data Policing.”