From Schneier on Security – Microsoft is Giving the FBI BitLocker Keys

 Microsoft gives the FBI the ability to decrypt BitLocker in response to court orders: about twenty times per year.
It’s possible for users to store those keys on a device they own, but Microsoft also recommends BitLocker users store their keys on its servers for convenience. While that means someone can access their data if they forget their password, or if repeated failed attempts to login lock the device, it also makes them vulnerable to law enforcement subpoenas and warrants. Read More