Domestic Assault charges should be taken seriously and should involve an attorney representing the accused.  A conviction for domestic assault could involve a jail sentence up to 90 days and a fine of $500 even on a first offense. In Missouri, the definition of assault is: 

(1) He attempts to cause or recklessly causes physical injury to another person; or

(2) With criminal negligence he causes physical injury to another person by means of a deadly weapon; or

(3) He purposely places another person in apprehension of immediate physical injury; or

(4) He recklessly engages in conduct which creates a grave risk of death or serious physical injury to another person; or

(5) He knowingly causes physical contact with another person knowing the other person will regard the contact as offensive or provocative.

If there is physical evidence of assault in the form of photos indicating bruising or "red marks," then the prosecutor will present those to the court at trial as evidence of an assault.  If the accused has no prior charges of assault and the alleged injuries are minor or non-existent (no indicators of actual touching) then the better approach would be to negotiate a reduction of the charge to "disorderly conduct."  This charge carries fewer penalties, usually involves paying a fine and avoidance of probation, and does not suggest any act of violence.  In other words, it lightens the blow on the criminal record and in effect masks any suggestion of violence.  The prosecutor may not agree to such a reduction of the charge, but it is certainly worth asking for if the circumstances warrant. 

In some instances, the victim may choose not to appear in court.  In this case, the accused should I either enter a Not Guilty plea and ask for a trial setting OR allow his attorney to plea bargain for a reduced charge (see above).  A plea agreement may be the best course of action if the offer is to amend the assault charge to a lesser charge, as mentioned above.  This is ideal for someone who wishes to avoid going to trial or who prefers to resolve the matter as soon as possible.  Generally, the prosecutor will request a continuance on the first appearance if the victim does not show up for court.  This simply prolongs the case but sets the stage for an outright dismissal IF, and only IF, the victim fails to show up for a 2nd time.  Generally, each side gets at least one continuance request, and the norm is generally two continuances each.  The court, however, has discretion on continuance requests and can grant as many requests as they wish. 

On a side note, some prosecutors will not amend a "domestic" assault charge if there is evidence of a battery, ie bruising or marking.  This policy is understandable and forces to the defense attorney to be creative in order to secure a plea bargain for his client. I often look for reconciliation efforts by the parties, or perhaps the parties have initiated couples counseling.  Regardless, the attorney should consider all positive efforts made by his client before deciding on a negotiating strategy.  I believe most prosecutors in Missouri (at least in Jackson County) are reasonable and will listen to most credible arguments in favor of a reduced charge plea agreement.