A factual statement - "The earth is round" - is true or false.
A normative statement - "You should not steal" - is different from a factual statement. A normative statement describes a rule for behavior: you should not do something (or more rarely, you should do something). This is the domain of ethics, morality, and law.
Without norms, life would be intolerable.
What can we say about norms? Why do people behave badly?
The political scientist Hans Morgenthau talks about how norms have two parts: the behavior described by the rule, and the sanction which occurs if you violate the rule. The sanction may be legal: the risk of being arrested and punished. It may be social: the risk of social condemnation and ostracism. Or it may be ethical: the guilt imposed by one's own conscience. Christoph Frei sums up: "'Thou shalt not steal' can be a command of ethics, mores, or the law. It is the sanction that differentiates these three types of rules of conduct."
Christoph Frei, writing in Hans J. Morgenthau: An Intellectual Biography (2001), pp. 135-137:
The psychic reality of a norm ... is founded on its "capacity to influence the will of the person it addresses" in the direction desired by the norm. But what enables the norm to have this effect? What will generally induce the person addressed by the norm to follow its prescription? Morgenthau argues that it is the fact that violation of the norm will have adverse consequences for the addressee: a penance, for instance, or a punishment, or simply remorse. More specifically, a norm will be followed if the adverse consequence threatened by the sanction for behavior in violation of the norm outweighs the advantage to be gained by acting in defiance of the norm.
... He concludes that it is not the content of the norm itself but the expectation of a sanction if the norm is violated - "a fear of displeasure" - that triggers the "stimulus of self-interest" in the person addressed by the norm and thus influences that person's behavior. If no sanction is expected, the norm has no psychically relevant reality, hence it lacks validity. It is "a mere idea, a wish, a suggestion, but not a valid rule." Thus, Morgenthau counters a "flawed positivist theory" with his own "realist" theory of validity: A norm is not valid just because it has been posited as such, but only once "its violation is likely to be followed by an unfavorable reaction," that is, once the expectation of such a reaction exists as a psychic reality in the person to whom the norm is addressed.
The sanction constitutes not only the conditio sine qua non for a norm's psychic reality but also determines its character. In other words, the distinction between law, mores, and morality as normative spheres lies, not in the content of a given rule, but in the modality of the sanction following upon the violation of that rule. "Thou shalt not steal" can be a command of ethics, mores, or the law. It is the sanction that differentiates these three types of rules of conduct.
Examples
What concerned Morgenthau was international law:
Karl Neumeyer, Morgenthau's teacher in Munich [in 1926 and 1927] had taught him that there was "no area in which the discrepancy between the content of the law and its actual impact on shaping reality [was] as marked and as predictable as in the field of international law."
... [Morgenthau's] most important conclusion can be summarized as follows: In contrast to the [domestic] order, the physical instruments for applying sanctions are not monopolized in the realm of international law; instead, they are decentralized. In fact, they are precisely in the hands of those to whom the norms relevant for maintaining peace are actually addressed, that is, the representatives of national governments. Obviously, these representatives will put their physical potential at the disposal of international law only when it furthers their respective interests of the day. Thus, the reality (effectiveness) of international law is completely dependent on constellations of power and national interest: "elle se trouve donc au plus bas degre de primitivité" - it is of the utmost primitiveness. "This reality depends almost exclusively and most often very directly on the will of the individual nations and their representatives, in other words, on those who are at the same time the subjects of international law."
The findings that Morgenthau had worked out theoretically in his Habilitation thesis were substantiated once again right after the publication of his research. Italy's war against Abyssinia (1935-1936) and the League of Nation's pathetic response to this aggression settled beyond a doubt whether "the theory that we have just proposed does or does not agree with the facts." Moreover, that crisis made it abundantly clear that for the time being one could not place much faith in legal norms and stipulations.
Another example (familiar to readers of Tintin) would be Japan's invasion of Manchuria in 1932. The League of Nations ordered Japan to withdraw from Manchuria. Instead, Japan left the League.
On the Internet, social norms are far weaker than in a face-to-face conversation. This results in a style of discussion which can be described positively as "freewheeling" and negatively as "a tidal wave of digital bile."
In The Hacker Crackdown: Law and Disorder on the Electronic Frontier (1992), Bruce Sterling describes the spectrum of computer-mediated communication, based on the degree of sanctions applied to the conversation:
Boards can be distinguished by the amount of effort spent in regulating them. First, we have the completely open board, whose sysop is off chugging brews and watching re-runs while his users generally degenerate over time into peevish anarchy and eventual silence. Second comes the supervised board, where the sysop breaks in every once in a while to tidy up, calm brawls, issue announcements, and rid the community of dolts and troublemakers. Third is the heavily supervised board, which sternly urges adult and responsible behavior and swiftly edits any message considered offensive, impertinent, illegal or irrelevant. And last comes the completely edited "electronic publication," which is presented to a silent audience which is not allowed to respond directly in any way.