Twitter are fairly transparent in their policies. You should read this if you want to get a sense for how a large social network can operate with "best practice

Twitter are fairly transparent in their policies. You should read this if you want to get a sense for how a large social network can operate with "best practices" -- at a level that's practical anyway -- with respect to protecting user information: https://support.twitter.com/articles/41949-guidelines-for-law-enforcement https://support.twitter.com/articles/41949-guidelines-for-la.... Of particular interest is their link to http://www.law.cornell.edu/uscode/text/18/2705 http://www.law.cornell.edu/uscode/text/18/2705, the part of the Stored Communications Act that allows a gov't entity to prevent the network from telling the end user about investigations under certain rules. You should also take a look at the EFF's best practices stuff, such as https://www.eff.org/wp/osp https://www.eff.org/wp/osp (dated).