According to this concept, many offenders are actually victims suffering from a myriad of "syndromes," labeled premenstrual, post-partum, post-traumatic stress, black rage, cocaine-induced psychosis, battered women's, battered children's, and xyy chromosome. Some experts feel that this "doctrine of victimology" is changing the legal system as defendants successfully challenge previously well-defined rules of law concerning self-defense and criminal responsibility. On the other hand, even though many jurors seem amenable to the idea that some crimes are excusable, on the whole, the courts are establishing stringent standards for the admission of evidence relating to any of the syndrome- laden defenses. One indication of the courts' conservatism on this issue is the difficulty of introducing these conditions as evidence for mitigating a sentence.