Being a district attorney has always been seen as a steppingstone to higher political office. The goal usually was to keep your nose clean, investigate your future opponents and only prosecute safe, easy cases. And when you are in a heavily Democratic state, you must also show your fidelity to liberal principles like excusing crime, looking the other way at corruption of your fellow dems and sounding right.
Hallinan's long-time aide was Ross Mirkarimi, who eventually became the Sheriff of San Francisco. Mirkarimi was accused of domestic abuse by his wife and later by another woman.
-PJ