In a tribe everyone knows one another. The tribe is the very maximum size where this is the case. Perhaps the law was made for strangers.
The very maximum size where what is the case?
If it's regarding the existence and enforcement of norms, that is not so. Even the most trivial of things that are not put down in law are socially enforced across vast populations. A consequence of the increase in cultural exchange between distant places due to technological advancements in communication/traveling.
In the vacuum left behind from the law and police monopoly on violence, people will organize into modular and overlapping communities out of necessity, and what ways of dealing with what kinds of norm deviancy would be regarded as appropriate by the rest of the community(/ies) will be discernible by individuals, discussed openly on forums, between friends and in community gatherings (offline and online) and change over time.
Transparency in investigation and proof required for asserting whether a particularly serious deviancy has occured will also be things that people will be uncomfortable without, and there will thus be a norm against wanton vigilantism.
In the end, for things to work smoothly, the wisdom and level of aversion to inter-community conflict of the people who are a part of the communities will have to be very high if they aren't going to require any specific laws of the "when someone does Y, we do X" variety.
I will describe a way to circumvent having laws when it comes to filling the role of "judgement".
A way to not compromise the fluidity and pragmatism possible in a non-law system is to have a process they usually use (subject to change or even there being multiple accepted alternative processes) in regards to how to determine if there potentially has occurred a norm deviancy and the process in which one deals with serious cases of norm deviancy, such as for example some form of massive jury where a certain % has to agree on what is a feasible course of action to deal with the situation (taking the role that the law would have in prescribing the solution). With maybe another consensus vote on whether that was a good solution or not from the whole of the community(ies) afterwards.
The specifics are not important for the illustration beyond describing that functions now held by police, lawmakers, courts and the penal system could be filled by a less rigid system. There can be non-rigid systems much different from the one I describe that can be functional.
Or when two communities who do things differently have an inter-community case, they could negotiate a process format. And the communities themselves would have to inside itself have some sort of semi-consensus (if egalitarian) on how to handle the process of negotiating.
The lines are blurry and one could argue the last two paragraphs are essentially laws, but there would not be any enshrined and outside-humans existing "when someone does Y, we do X". The final say on the course of action is still norm/culture & case by case dependent, and specific processes only exist so long as people agree to them existing if there is no monopoly on violence to protect anyone who thinks they have authority from the majority.
