There’s a price that you pay for convenience. If law enforcement wants to peer into everything that you do on your iPhone, all they have to do is nab a copy of some off-the-shelf software from ElcomSoft. The forensics tool is able to retrieve all the data that you have backed up on iCloud.
Yes, the iCloud online backup service is convenient for you, but also means that inquiring minds can effectively gain access to a near real-time copy of all that data. This includes your email messages, call logs, website visit history, text messages, and more. Your data is automatically backed up by iCloud each time it comes in contact with a Wi-Fi access point.
Under normal circumstances, the police would need physical access to your phone in order to tap into all those records. Assuming that they have the proper warrant and everything, law enforcement can presumably get access to the associated Apple ID and password, using the ElcomSoft solution to snoop through those backups in real time. This is even better than tapping into phone calls.