In Greg's response to the question of Is smoking immoral?, Greg wrote:
I know that even in a private establishment, you are not allowed to shoot another person or beat them with a stick even if you put up a big sign that says "shooting or beating people allowed". How does that apply to things like second hand smoking?
Second hand smoke can be a rights violation, depending on the context. Second hand smoke can also not be a rights violation, depending on the context. It all depends on whether or not you have objectively consented to the imposition of the second hand smoke.
In general, the imposition of any physical contact with your person that you have not objectively consented to (including contact with noxious gases) is a rights violation. If you objectively consent to the contact, it is no longer a rights violation.
However, objective consent does not necessarily require you to explicitly consent to the contact—for example, you do not have to verbally say "I consent to you touching me" for you to have objectively consented to my touching you. Consent can be implied , based on a person’s objectively observable actions and the surrounding context. For example, when you reach your hand out to me in the familiar "hand-shake" gesture, it is clear that you have objectively consented to my grasping your hand in a hand shake.
One category of objectively implied consent is consent to the type of bodily contact that is normally incident to the performance of a given activity---by voluntarily engaging in such an activity, you objectively consent to all such bodily contact that is normally incident to that activity. For example, when you ride the subway a certain amount of incidental physical contact with your fellow riders is to be expected (and is probably even unavoidable )—people will brush against you as they enter/exit, people will bump into you as the train changes direction, people’s breath will fall upon you, etc. By choosing to ride on the subway, you consent to all such physical contact that is incidental to the activity. (obviously implied consent, like all consent, has contextual limits, and thus it is not the case that you consent to all contact by engaging in an activity—e.g., you do not consent to being sexually groped merely by riding the subway, since sexual groping is not normally incident to riding the subway (in most locals)).
Applying these principles to second hand smoke, it should be clear that when a person enters an establishment that has a sign warning that smoking is going on inside, that person has impliedly consented to the imposition of the second hand smoke. The physical contact of the noxious fumes with your person is contact that is normally incident to the activity of entering an establishment where smoking is permitted, and thus by voluntarily entering such an establishment you have consented to such contact. On the other hand, you have not necessarily consented to, for example, someone coming up to you and blowing smoke directly in your face—again, implied consent has contextual limits.
Thus, by posting a sign the owner of an establishment has not somehow dictated what constitutes a rights violation on her property—she has no power to dictate what does and does not constitute a rights violation. However, the owner does have the power to require you to consent to something as a condition for entering her property. By posting the sign, what the property owner has done is merely established consent to second-hand smoke as a condition for being admitted into her establishment. The fact that you do no verbally state you consent is immaterial, since your consent is objectively implied by your voluntary action of entering the establishment after having seen the sign. If you do not agree to the condition (i.e., you do not wish to consent to second hand smoke) then you are free to not enter the property.
Note that objective consent is not the same thing as subjective consent. It is possible for you to have objectively consented to something even if deep down inside you really really really do not want the thing to happen. What you want is immaterial; what you objectively demonstrate—through word or action—is what counts with regard to objective consent. The classic case on this point is a girl who was in a line of new immigrants getting vaccinations as a condition for entering the country; she presented her arm to the doctor and did not signal any objection (verbally or otherwise) to the vaccination, but then later tried to sue the doctor for battery on the grounds that she did not consent to the vaccination. The court correctly held that she had impliedly consented by standing in a line of people who were getting vaccinations, presenting her arm to the doctor, and failing to object. The court also correctly held that her sincere desire to have not been vaccinated did not nullify her consent, because all of her objectively observable actions indicated consent.
As for being shot or beaten, yes, it is possible to consent to these things (boxers consent to being hit by their opponent, for example). However, because these things are objectively more serious than, for example, the types of incidental physical contact occurring on the subway, the requirements for finding consent in the case of being shot or beaten will be much more strict than in the case of incidental jostling in public or second-hand smoke. In particular, because shooting/beating are so serious, it is imperative that we are certain (1) that the person did in fact consent, (2) what the actual scope of the consent was (and whether it exceeded). A sign on a door may be insufficient to provide us with the required certainty in these serious cases, and accordingly, it is proper to require something more than a sign on a door in order to find consent in the case of shooting/beating. Just because a sign might be sufficient to imply consent to one thing does not necessarily mean that a sign is sufficient to imply consent to something else.