Can my wife have the charges dropped in a domestic violence case?

The decision whether or not to prosecute a case (i.e. whether or not to drop charges) rests with the prosecutor and not with the alleged victim.  What that means, from a practical standpoint, is that a case may be prosecuted over your objection.  While the states case would be stronger with your testimony, if there is other evidence to support the charge the case may still go forward. That being said, a skilled criminal defense attorney may be able to use the fact that you do not want to cooperate as leverage to obtain a favorable result for the defendant (i.e. to potentially have the charges dismissed or otherwise resolved favorably).  However, prosecutors are often very unwilling to simply drop these types of cases, particularly, because they do not want to send the message to offenders that, if they can intimidate or otherwise unduly influence a victim, they can get away with what they have done.  Note:  If you are subpoenaed you must show up or you can be held in contempt of court and jailed. Bottom line, you will need to speak with an attorney as to all of this.