My client had been injured because of defective building maintenance. As is customary in such cases, we didn't limit our claim to the physical injuries but added the psychological ("loss of enjoyment of life" is the usual term).
Whenever a plaintiff claims injuries of any kind, the defendant is entitled to explore possible alternative causes. In our case, the judge allowed the defense lawyer to present evidence of the plaintiff's prior abortion, and to argue to the jury that it was wholly or partially responsible for the psychological issues that she was asserting.
The Mehos case is different. The husband's attorney said that the wife was "a woman who complains that she’s under great stress only caused by Mr. Mehos," which would open the door to evidence about other causes of stress. The weakness in that argument is that I don't think a divorce proceeding would normally include a claim for damages for stress; that would have to be a separate action.
The care2 site that's linked in the OP imputes a different rationale: "The idea being presented is simple: A good mother would never seek out an abortion, so if she ends a pregnancy, she must be an unfit one." That's a gloss by care2, completely unsupported by the underlying news story.
That story gives the impression that the relevance wasn't so much the abortion as the pregnancy:
The judge sided with Alter (the husband's attorney), noting that Lisa Mehos had previously testified she had never had any men over to her New York apartment. “I do find it to be relevant. The children were in her care at the time,” Sattler said.
Lisa Mehos, 38, then testified that she became pregnant after a one-time fling with a longtime friend at his place.
This leads me to think that the argument was: She had an abortion, therefore she'd gotten pregnant, therefore she had sex with a man, therefore this man might have been visiting her when the kids were there so that they were "exposed" to him (and, presumably, to this promiscuous conduct). That's a pretty tenuous line of reasoning, but it's unfair for care2 to raise a strawman of "anyone who gets an abortion must be an unfit mother."
Incidentally, if anyone cares, my case ended well. The jury returned a very low verdict for my client. Jury verdicts are often reduced if deemed excessive by the trial judge and/or the appellate court, but the power runs both ways (although rarely exercised). We successfully argued that the verdict was unreasonably low, because the jury had been improperly influenced by the evidence about her abortion and by other factors. On that basis we got the damage award increased -- the only time in my career that I've seen this happen.
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