California Location Privacy Act of 2012
This 2012 bill would require a warrent for law enforcement to obtain the location of a mobile device, with the exception of being able to respond to the user’s call for emergency services, with the consent of the owner or user of the electronic device, or in an an emergency envolving immediate danger of death or serious physical injury to the owner or user. Note: You can make an emergency call from a charged phone, without a plan, though I have not tried this for myself.
Like the security problems with the HTTP protocol that allow for network sniffing, the design of the mobile phone network is flawed in that the location of every device must be known for the system to function. The location privacy could be a part of the security of the communications system.