And here's a case of how California Highway Patrol officers used to pass around pictures from phones they scanned https://www.sfgate.com/crime/article/Disturbing-texts-in-CHP...
Basically, beyond the general ethics that should restrain individuals from non-consensual distribution of intimate imagery, and the policies on social networks and other institutional environments banning this kind of activity, lies the domain of law enforcement... and if they have the ability to access people's phones like this then they have an obligation to be scrupulous about their behavior