As an Assistant D.A., I spent 6 months as the Chief Prosecutor covering only family violence type cases. These are unique cases in many ways. By understanding where the history of this comes from, it can truly help in defending my clients who are now charged with these types of cases.
In the 1990's, there were several high-profile murders where there had been some previous allegations of family violence assault between a man and a woman. Police were called out and they told the couple to "cool off" and did not make an arrest. Police felt like this was between the couple and no arrest was necessary. Shortly thereafter, the man would come back in a fit of rage and kill the woman. The police were questioned by media and society about the lack of action taken in the first calls out to the home. Police departments were sued and had to rethink their policies.
For the past 25 years, when the police are called out and anyone mentions anything about an assault or a threat – someone will be arrested. There may not be enough evidence to convict them. The "victim" may be telling the police not to arrest them. In fact, many times, someone initially calls the police because they just want the other person to leave the home. They have no idea that the police will arrest someone!