Her boss found her too irresistible. He complained that if she saw his pants bulging, she was dressing inappropriately. He texted to ask how frequently she experienced orgasm. He said that, for a woman with a body like hers, not to have sex often was like having a Lamborghini in the garage and never driving it.

Then, after 10 years of employing her, he fired her. James Knight, the boss in question, is a dentist based in Fort Hood, Iowa. The employee, Melissa Nelson, is a dental assistant. She is married with one child, and is agreed by all parties to have been an exemplary employee. Indeed, she seems to have tolerated more for the sake of her job than most people have to.

What Nelson is alleged to have done to deserve the sack is to constitute a threat to Knight's marriage. The problems began in the year and a half before the sacking. On several occasions, Knight complained that her clothing was "too tight" and revealing. About six months before the sacking, the texting began. While Nelson was willing to engage in text exchanges, she reproved him when he told her off for wearing a shirt that was too tight, and refused to respond when he asked her how frequently she experienced orgasm.

Some time before the sacking, Knight's wife, who also worked at the dental surgery, discovered one of the text exchanges on his phone. Rather than demanding that he change his behaviour, she insisted that he fire his employee. The couple consulted their pastor, and the pastor agreed: the woman had to go, for the sake of his marriage.

All of this may seem ridiculous. Indeed, it seemed sufficiently ridiculous for Nelson to take her former boss to court with the intention of suing him for sex discrimination. But the all-male panel of seven judges in the Iowa district court, which threw the case out on 21 December, saw nothing amiss. As far as Judge Mansfield was concerned, to allow a case for sex discrimination in this instance would stretch the definition of discrimination.

The judges' rationale was that the employer was motivated by emotions, above all by his commitment to his marriage, and not by gender prejudice. "Ms Nelson was fired not because of her gender but because she was a threat to the marriage of Dr Knight," the judgment says – thus identifying the blameless employee as the problem, rather than the wayward behaviour of Dr Knight.

The assumptions and the nature of the inferences made in the court's judgment all reinforce patriarchy in its dominant "family values" register. It consistently identifies the victim as the problem. It alludes to allegations by Knight's wife that Nelson flirted with her boss. Yet all the specific evidence it describes shows that Nelson put up with, rather than instigated or encouraged, flirting. The judgment notes that Nelson did not tell her boss that she was offended by his texts and that their texting was mutually consensual. Rather than considering the power relationships condensed in such exchanges, the court tacitly identifies the woman as the temptress.

Yet the court's behaviour was not some wild aberration. The legal justification for the decision may be intensely ideological, but so is all legal reasoning. The judges were able to cite ample precedent for their decision. "Several cases," they noted, " … have found that an employer does not engage in unlawful gender discrimination by discharging a female employee who is involved in a consensual relationship that has triggered personal jealousy. This is true even though the relationship and the resulting jealousy presumably would not have existed if the employee had been male."

Despite acknowledging that the situation as such can occur only in a relationship between male employers and female employees, that gender does indeed occupy the key determining place, the court refused to "stretch the definition of discrimination" that far. Essentially, even if an employee is at no fault, as long as she is female this is just one of the burdens she has to bear. The responsibility is on her, not her male employer, to safeguard against eroticism – on pain of being fired.

At each step, Knight, his pastor and, to an extent, his wife – and certainly the Iowa district court – fell back on and fortified a particular knot or intersection of power (business, family and church). This knot might be called capitalist patriarchy. And its full arsenal – political, moral, legal, cultural – has just been placed behind sexist employers.