Re: domestic abuse
If the person who was not arrested did in fact assault and/or batter the other (who was arrested), the person arrested can attempt to bring a "cross complaint" against the other for criminal charges relating to the incident (similar or identical charges).
Because there was no arrest, however, the "complainant" (the one seeking to bring cross complaint for A&B), needs to go to the district court in the town or county where the incident occurred. Tell the clerk you would like to bring a criminal complaint relating to the incident. You'll fill out a form and probably describe what happened. Then the court will set a hearing before a clerk magistrate, who will decide whether the facts support the filing of a criminal case against the assailant, who will have an opportunity to argue why no charges should issue.
Many, if not most, assault and battery cases result in "cross copmplaints" like you might be seeking here. Each person claims the other was responsible for the altercation and, unless there are witnesses, its one person's word against the other. Sometimes, depending upon the criminal history of those involved, courts will simply dismiss both cases, rather than have two trials relating to the same incident.
If you were the one arrested, and the other person assaulted you (but wasn't arrested), you would be well served to bring a complaint against that person, which you can use as leverage to get a favorable disposition of your criminal case. I can help you along; just contact me.
