In Germany they have used the health data collected on the iPhone to help in a criminal muder trial. They used it as it showed he may of been climbing stairs which could correspond him climbing a river bank after dumping the body.
After the suspect was arrested he would not hand over the code to unlock the phone so they got an external copy in Munich to do this for them.
To help with the data, the recreated the climb down the bank and up and again the app showed the same data and put it down to climbing stairs. So with the health data and combined geo data they could pinpoint him to the place.