THE HUSBAND AND WIFE CAME TO COURT together, as assailants and victims in domestic violence cases often do. When the judge asked how the assailant pleaded, she looked at her husband and replied, ruefully, "Not guilty." The assailant, as sometimes happens, was the wife -- a minister who came to her sentencing in a smart black-and-gold dress that had doubtless been worn more to church than to court.

It was the husband who explained. One afternoon a year after their marriage, he took off his wedding ring because of the heat. That bothered his wife; her angry questions bothered him; in the ensuing argument he questioned her "spirituality," and, enraged, she grabbed him. After restraining her, he called 911, hoping the police would help cool things off. Instead, to his shock, they arrested his wife.

"We didn't know about the new law," the man told the judge. He was referring to a Virginia law, which took effect in July 1997, mandating arrest in the case of domestic assault and battery.

I happened to be in the courtroom that morning, watching the parade of human misery on what might be called domestic violence day -- every Thursday -- in Fairfax County's Juvenile and Domestic Relations Court. A more varied look at love's dark side would be hard to find; also in court were a grown son arrested for pushing his mother down on a bed, a young woman arrested for pulling her boyfriend's hair, and a man arrested for pushing his girlfriend down the steps, even though -- he claimed -- it was the girlfriend who pulled him down the steps and it was his arm that was broken. All kinds of emotional explosions, all ending in one thing: arrest, thanks to the Virginia law, one of the nation's strictest.

Given this law, it was curious to learn, last month, that another argument in another troubled Virginia household ended short of court. This time -- at 7:20 a.m on June 23 -- police were called to the Alexandria home of U.S. Rep. James Moran after his wife, Mary, called 911 to report a domestic dispute. What happened was -- as usual in these cases -- hard to figure, since the stories were muddy and changing. But according to the police, both parties did agree there was physical contact, when the "male resident" (the police would not use names) grabbed the "female resident" by the upper arms while walking past her.

Beyond this, Alexandria would not release the full police report. But based on these details, it seems reasonable to wonder why the Morans didn't end up where tens of thousands of other citizens do: namely, telling their humiliating tale to a judge. Under Virginia law, police must make an arrest if they have probable cause to believe a domestic assault and battery was committed -- battery, as defined by Commonwealth's Attorney S. Randolph Sengel, being "any bodily hurt, however slight, done to another in an angry, rude or vengeful manner." In cases of mutual combat they are directed to identify and arrest the "primary aggressor" -- as they did with the minister, deciding that it was she, rather than her husband (who restrained her), who committed battery. The goal is to pinpoint the real combatant: the one who threw the plate (no) or the one who responded by seizing a hammer (yes).

In this case -- after interviewing the Morans, calling the chief magistrate for his opinion, and phoning the commonwealth's attorney to see if Moran qualified for congressional immunity -- the police left, saying they could not identify the real combatant. "This was a clear case of he-said, she-said," said Police Chief Charles E. Samarra -- oddly archaic language to use in a time when domestic violence laws exist to compel police to sort out he-said, she-said situations, something they were notoriously loath to do back in the bad old days when feuding couples were left to sort things out themselves. Much as -- come to think of it -- the Morans have been left to do, their response being to move toward divorce.

The point is not that an arrest should have been made. Certainly one hates to see a couple hauled into court as the result of a temper tantrum, particularly one whose marriage has been as stressed as the Morans', not only by public life but by the personal agony of having a child fighting cancer. No, the point is this: How many ordinary citizens merit a call to the chief magistrate while police are dithering about how to enforce a subtle and controversial law? Even as one sympathizes with Moran's request for privacy, one wonders whether he was granted a wider zone of privacy than the fractious minister. Indeed, in these days when everybody seems to think the private lives of public figures are over-scrutinized, one wonders whether simply by dint of their stature, lawmakers are in fact shielded from the unintended consequences of the laws they've supported. It will never be known whether this male resident -- a liberal Democrat who has sponsored domestic violence awareness events in his own working-woman-filled district -- grabbed this female resident in anger or self-defense. Yet the spouse-grabbing minister -- ordered by a judge into counseling -- has an arrest eternally on her record, for all the world to see.

Liza Mundy's e-mail address is mundyl@washpost.com.