Though dozens of cases invoking the "unwritten law" would be heard in American courts by the end of the 19th century, homicidal jealousy was limited to men. Any woman committing murder under similar circumstances would be prosecuted to the full extent of the law. This became abundantly clear in the case of Kate Southern, a Georgia woman who was charged with murdering a rival for her husband's affections in early 1878.
According to the lurid news coverage, Kate had married her husband, Bob Southern, despite the active opposition of Narcissa Fowler (frequently described in the newspaper coverage as a "woman of notoriously lewd character") who had been sexualyl intimate with Bob before, and after, his marriage. Though Kate knew about the affair and had been "unsettled and annoyed by the knowledge", she seemed determined to keep Bob and Narcissa as far apart as possible. Narcissa actively tried undermining Kate's marriage, including starting scandalous rumours about her and saying that "they would have no peace or satisfaction as long as (Narcissa) lived."
A few months after Kate and Bob were married, Narcissa confronted Kate at a party where, under the influence of the whiskey she had been drinking, she began insulting Kate using what one witness later described as "epithets too vulgar and obscene to be written or spoken." After finally provoking Kate into a fistfight, Kate's sister, Amorelli Hambrick got involved as well. Though Narcissa likely had no idea that Kate was armed with a knife, she learned this quickly enough when Kate stabbed her repeatedly. The newspaper coverage fails to mention whether Narcissa died at the scene or later but Kate promptly fled. Joined by her husband and other members of her family, she became a fugitive until a posse eventually tracked her and her husband down. After being returned to Pickens County where the stabbing occurred, Kate Southern was subsequently charged with murder. Her sister was charged as an accomplice while her husband was charged with helping her escape.
The legal defense that Kate received at her trial was far less spirited than what Daniel Sickles managed to arrange. Many observers accused Kate's lawyers of mismanaging her defense but their legal options were fairly limited. There was certainly no question of seeking any kind of defense based on the "unwritten law." Though husbands could claim that a wife's infidelity was an attack on their "personal honour", wives were expected to endure the extramarital affairs of their husbands in silence. Women could claim self-defense if they were being raped but killing an unfaithful husband or the other woman typically led to a criminal conviction. Presumably, the courts didn't feel comfortable giving wives the same "license to kill" that husbands enjoyed.
And so it was with Kate Southern. It probably didn't help that her defense attorneys failed to launch much of a defense on her behalf. Many of the newspaper reporters commenting on the trial openly criticized the lawyers for not calling any witnesses on Kate's behalf or their failure to cross-examine many of the witnesses that were called. All that they were able to come with was a half-hearted insanity defense which failed to convince the jury. Her conviction hardly came as a surprise to anyone though the penalty handed down by the judge certainly was. Kate Southern was sentenced to death by hanging.
Almost immediately after news of the sentence got out, the campaign to save Kate's life began to mobilize. Her attorneys mounted an appeal to Georgia's Governor to commute the sentence. This included numerous depositions from Kate's family members (including her husband) which attempted to show that she was provoked into killing Narcissa. It also helped that Kate had recently given birth and descriptions of Kate in prison with her baby where she awaited her execution helped the media campaign to save her life. Petitions with thousands of signatures (mostly women) were sent pleading for clemency.
The campaign worked. Kate'a sentence was commuted to ten years in prison to be spent in a Georgia prison camp. Her sister, Amorelli, was sent to the same camp to serve her own sentence. Thousands of supporters came out to watch the train that would take Kate to prison. As one newspaper description reported, "at all the towns through which the train passed, the people (ministers, gamblers, women, and all classes) crowded to the depots to see and express their sympathy for her, and at Atlanta, where a large purse was collected for her benefit, the excitement was so great that the car windows were broken." Her husband found work near the prison and was even granted conjugal visits (Kate had two more children during her time in prison). After serving only three years of her sentence, she was granted a full pardon and allowed to return home.
Kate Southern largely faded into obscurity after she was released but her case continued to generate controversy. In the years that followed, more conservative newspaper editors accused Kate's supporters of allowing her gender to save her from execution and argued against granting clemency for women committing murder. And there would be no more clemency. When Emma Simpson shot her estranged husband in 1919, believing that "the new unwritten law, which does not permit a married man to love another woman, will be my defense," even Clarence Darrow couldn't save her from being found "insane but guilty."
While the number of cases claiming the "unwritten law" became less frequent by the 1920s, husbands committing murder to defend their "personal honour" still used the defense well into the 20th century. In many U.S. states, the law allowing husbands to kill "interlopers" was formally enshrined into legal statutes (thus making it the "written law"). When and where the law could be used became a major sticking point for many judges who insisted that husbands could only kill their wive's lovers if it was done in the "heat of passion." If the husband allowed time for his anger to cool and to become more reasonable, then any homicide committed afterwards became "deliberate revenge" and he could be prosecuted.
In Texas, for example, one statute held that, "Homicide is justifiable when committed by the husband upon one taken in the act of adultery with the wife, provided the killing take place before the parties to the act have separated. Such circumstance cannot justify a homicide where it appears that there has been, on the part of the husband, any connivance in or assent to the adulterous connection." In other words, the couple had to be caught in flagrante delicto for the killing to be legal (it was eventually repealed in 1974). Other states, including Georgia, New Mexico, and Utah passed similar law, almost all of which would be repealed by the end of the 1970s.
Today, whhile husbands are no longer so free to kill to avenge "personal honour", the "temporary insanity" or "diminished capacity" defense is still around in one form or another. Perhaps fittingly these days, it is more likely to be used by women on trial for murdering their husbands due to domestic abuse (a.k.a. the "battered woman defense") than vice-versa. Whatever the status of "unwritten law" today however, defense attorneys are still known to use it during murder trials simply because it might work. There is often no telling what a sympathetic jury might decide to do in cases where they regard the husband (or wife) as being fully justified in committing murder in the heat of passion.
And so, the legacy of Daniel Sickles and Kate Southern remains with us even today.