Disregarding the fact that it is not, in fact, legal to do with one's body what they will in an absolute sense (it is not legal for minors to consume alcohol, it is not legal for persons to consume certain drugs, etc.), there can be noted some circumstances in which a person's body/bodily resources can be used/treated against a person's will. Though Pro-Choicers generally ask for one such circumstance, I'm going to list more than one, simply to further a point.
1. During criminal investigations, or during paternity testing, a court can order a blood draw / DNA sample against the will of the person whose DNA / blood is to be obtained.
2. Assisted Outpatient Treatment: This is when someone is court-ordered to take medication/treatments (say, for severe mental illness). Should the patient refuse, they can be hospitalized involuntarily for further treatment. This is legal in 45 states. It has also been upheld in court challenges.
3. Let's say someone attempts suicide and is discovered by a relative, who calls the police. First, they can be taken to the hospital involuntarily. Second, if they are deemed mentally incompetent, they can be forced to be treated even if they refuse. Third, if they are considered to be a danger to themselves or others (even if they claim that they are no longer suicidal but are not believed by the psychiatrist), they can be involuntarily committed to the hospital against their will and even if they are not admitted at that time, doctors can still obtain a court order to involuntarily have them admitted later.
4. Doctors have forced C-Sections on women who have refused. Courts have sanctioned this--and ordered it to be done. Doctors can obtain a court order to perform a C-Section even if the woman refuses.
5. If abortion is illegal or even restricted, if a woman falls in the situation where, say, her pregnancy does not qualify for a legal abortion, then the fetus/unborn child is allowed to use her body against her will. She might be too far along. She might not be in life-threatening danger. It depends on what the abortion laws are for this one. Pro-Choicers may not agree with this, but that does not mean that it is not true, and, in many cases, legal.
I'd like to recommend as a follow-up: Six Ways in Which the Government Controls Your Body
Bodily autonomy is never absolute, and can never be absolute.
