The crime of assault generally requires that both the perpetrator and the victim of an assault be a natural person. Thus, unless the attack is directed by a person, an animal attack does not constitute an assault. However, under limited circumstances the Unborn Victims of Violence Act of 2004 treats a fetus as a separate person for the purposes of assault and other violent crimes.Possible examples of defenses, mitigating circumstances, or failures of proof that may be raised in response to an assault charge include:

Lack of intent: A defendant could argue that since they were drunk, they could not form the specific intent to commit assault. This defense would most likely fail, however, since only involuntary intoxication is accepted as a defense in most American jurisdictions. Mutual consent: A defendant could also argue that they were engaged in mutually consensual behavior. For example, boxers who are fighting in an organized boxing match and do not significantly deviate from the rules of the sport cannot be charged with assault. State laws
Laws on assault vary by state. Since each state has its own criminal laws, there is no universal assault law. Acts classified as assault in one state may be classified as battery, menacing, intimidation, reckless endangerment, etc. in another state. Assault is often subdivided into two categories, simple assault and aggravated assault. Simple assault involves an intentional act that causes another person to be in reasonable fear of an imminent battery.
More advanced disease shows more obvious symptoms or signs that can be detected on a physical examination. The uterus may become enlarged or the cancer may spread, causing lower abdominal pain or pelvic cramping. Painful sexual intercourse or painful or difficult urination are less common signs of endometrial cancer. The uterus may also fill with pus (pyometrea). Of women with these less common symptoms (vaginal discharge, pelvic pain, and pus), 10–15% have cancer. Risk factors
Risk factors for endometrial cancer include obesity, insulin resistance and diabetes mellitus, breast cancer, use of tamoxifen, never having had a child, late menopause, high levels of estrogen, and increasing age. Immigration studies (migration studies), which examine the change in cancer risk in populations moving between countries with different rates of cancer, show that there is some environmental component to endometrial cancer. These environmental risk factors are not well characterized. Hormones
Most of the risk factors for endometrial cancer involve high levels of estrogens. An estimated 40% of cases are thought to be related to obesity. In obesity, the excess of adipose tissue increases conversion of androstenedione into estrone, an estrogen. Higher levels of estrone in the blood causes less or no ovulation, and exposes the endometrium continuously to high levels of estrogens. Obesity also causes less estrogen to be removed from the blood. Polycystic ovary syndrome (PCOS), which also causes irregular or no ovulation, is associated with higher rates of endometrial cancer for the same reasons as obesity.