[sgk284]

The batteries only last a handful of hours so officers turn them on as necessary (also most police unions lobby for this ability). It's unfortunate but it's the current reality.

[dghf]

So how do they, as the article says, "retain footage 30 seconds before an officer presses the record button"?

[honestoHeminway]

The permanently record, but do not permanently store. So if a button is pressed, they store 30 seconds of pre-recorded footage.

[syshum]

Most police body cam models have batteries that last for 12 hours of recording, enough to record an entire shift