It is important to recognize that Orwell’s novel is, in reality, an allegory to the Soviet Union under the brutal Stalinist regime. Laws do not exist precisely because (and readers of Orwell should have this in mind when evaluating his narrative) the omnipotent Party that rules Oceania is a direct reference to the situation in the Soviet Union under Stalin, in which the Communist Party was considered the manifestation of the will of the people, operating within a society that considered itself to be governed by the liberated working men and women (the proletariat). As such, the formal codification of laws should have been hypothetically unnecessary, as any action taken by an individual in socialist society was theoretically representative of the will of the whole. In this scenario, society itself had (presumably) broken down all forms of social hierarchy and inequality.
In the Soviet Union, however, this was demonstrably not the case, and Orwell uses the fictional setting of Oceania to allude to the terror faced by people of the Soviet Union under Stalinism. As such, those people who are killed, vaporized, or otherwise disposed of are symbols of both the absurdity of utopian promises and the corruption of the Party leaders. For example, early on Winston Smith recounts a movie he saw in his journal, in which refugees (presumably people trying to flee Oceania) were mercilessly gunned down by attack helicopters. These people, once citizens of Oceania, are portrayed as counterrevolutionaries and thus anathema to the utopian project that the Party and Big Brother are trying to construct. The very fact that Smith is maintaining a diary at all is extremely dangerous, as discovery of forbidden paraphernalia such as personal journals is grounds for immediate execution. Another example from chapter 6 has Smith recollecting a stranger he had passed in the street:
Your worst enemy, he reflected, was your own nervous system. At any moment the tension inside you was liable to translate itself into some visible symptom. He thought of a man whom he had passed in the street a few weeks back; a quite ordinary-looking man, a Party member, aged thirty-five to forty, tallish and thin, carrying a brief-case. They were a few metres apart when the left side of the man’s face was suddenly contorted by a sort of spasm. It happened again just as they were passing one another: it was only a twitch, a quiver, rapid as the clicking of a camera shutter, but obviously habitual. He remembered thinking at the time: That poor devil is done for. And what was frightening was that the action was quite possibly unconscious. The most deadly danger of all was talking in your sleep. There was no way of guarding against that, so far as he could see.
Here, even unconscious bodily movements are liable to betray one’s loyalty to society and doom them to extinction.
The overarching point Orwell is trying to make is that in Oceania, as it was in the Soviet Union, “law” in a formal sense has become obsolete. Instead it has been replaced by a kind of internal terror that has been deeply embedded in the psychology of every man and woman in society. This terror has hardwired a subconscious, mechanistic, imperceptible behavior in all of Oceania’s citizens so as to preclude the need for alternative forms of enforcing authority. People who break this pattern of behavior, even in the slightest, most inconspicuous way, are considered to be threats. Thus, it is not “laws” they are breaking but rather a specific kind of behavior that reinforces their own abject subordination.
The most horrible aspect of it all, however, is that the citizens of Oceania (as was the case of those in the Soviet Union) are taught that their behavior, their unbridled, euphoric love of Big Brother and the Party, are really just expressions of their own freedom. Through the megascreens and propaganda pamphlets throughout the city, people are led to believe that their daily actions create a society that is truly divine, free from crime, and the embodiment of human liberty and egalitarianism. Thus, their very existence has been turned into complete hypocrisy.