We post the law-enforcement guidelines and we require that if you're seeking non-public—so, private, personal—information about our Twitter users, you provide us appropriate legal process, so a subpoena or court order. This is in the interests of protecting our users' privacy.
We also are committed to transparency around law-enforcement requests, so we always notify users when someone has requested their information in this way. This would be the process we would ask parties to pursue if they were looking to receive information.