A good article from over on the EFF website.
https://www.eff.org/deeplinks/2013/01/google-twitters-new-transparency-report-shows-increase-government-demands-sheds
Quote
Twitter had over 3000 requests for takedowns, yet they only complied with 53%. That means almost half of all requests were invalid. It is again to Twitter’s credit that they both publicized this data and have committed the legal resources necessary to protect their users from invalid legal requests
https://www.eff.org/deeplinks/2013/01/google-twitters-new-transparency-report-shows-increase-government-demands-sheds