Res extra commercium

Res extra commercium (lat. "a thing outside commerce") is a doctrine originating in Roman law, holding that certain things may not be the object of private rights, and are therefore insusceptible to being traded.
Usually the doctrine encompass entities such as humans, public areas, organs, citizenship, prositution, etc. The doctrine is a exception to the general principle of Freedom of contract. Liberal legal systems assumes that whenever the sides to the contract consents to its conditions freely and informed, with no coercion of any kind, then there's no justification to limit their agreements. The liberal approach suggest that consent renders the contract desirable, and thus the state should not interfere.
In some contexts, the doctrine can refer to areas beyond national borders, such as space and the seabed; "these regions are subject to a common freedom of exploitation without exercising national sovereignty."
If one conceives of a world community made up "of sovereign, territorial states ... [the implication is] that the space between these states is res extra commercium, a space that, because of its position and function within this community, is disassociated from the full package of rights to possession, exclusion, and alienation that normally may be claimed by holders of property."
A recent move by Indian Government (February 2018) to curb the $11 billion tobacco industry's legal right to trade, the government, for the first time, has asked the Supreme Court to classify tobacco as “res extra commercium”. The move is part of the government's effort to tame the tobacco companies looking to challenge tough regulations pertaining to the industry.
Liberal vs. Non-Libaral Justifications
It is common to distinguish between libearl and non-liberal justifications of the doctrine. Even within the liberal approach, a diagression from freedom of contract principle can be warranted, as for lack of fairness, or flawed consent. For example, regarding prostitution, some liberals suggest it should be prohibited because it is normally consisting of coercion or flawed consent, and thus not really a manifistation of free trade. Similarily, a liberal might say that prostitution exposes those who engage in it to risks of sexual offenses and violence (for example because enforcement of breaches of agreements would not be effective), and so it should be banned, for similar reasonsing as we ban construction works without proper protection, or demand the wearing of a seatbelt.
On the other hand, the doctrine can be also justified by non-liberal arguments, such as moral enforcement or religious dogmas.
Some scholars suggest there are non-liberal justifications from a different kind, having to do with violation of civic liberty and human dignity. According to such views, which is considered non-liberal, it is the intervention in freedom of contract that better fulfills civic liberty. Philosopher Michael Sandel argues that some things are intrinsically bad in certain practices, such as organ trafficking or surrogacy, that has nothing to do with whether or not the people involved in them have freely consented. In surrogacy for example. Sandel argues that it errodes the value of childbearing and distorts it, and it shouldn't be commodified. Sandel explains that even sell of labour can ammount to an unethical damage of civic liberty, when a person sells his labour in an unhumane conditions. Sandel notes that the problem here is not with lack of consent, but because of the infridgement of human dignity.
References
Legal rules with Latin names
International law