If the abuser isn't present when the officer arrives, the officer has to do a report. That report goes to the state attorney's office and THEY decide if the case will result in charges and the pursuit of a warrant for arrest.
If your abuser is on scene when the police arrive, and the officer has probable cause to believe that domestic violence has occurred, they may be REQUIRED by law to make an arrest - even against your wishes. The reason for this is: a crime has been committed. Assault and battery (activities that are part of domestic violence) are crimes - and just like it's a crime to slap a stranger on the sidewalk, it's also a crime to batter someone you know or are in a relationship with. Having a relationship with a person doesn't make it ok for them to commit the crime of domestic violence against you or to damage your children by exposing them to violence against you. Crimes are considered to be committed against ALL of us...against society as a whole...not against individuals.
exerpt from>>>
http://www.aardvarc.org/dv/cops.shtml