The legal system must above all be predictable, and you’ll have a very hard time being predictable if your legal rules are written like “citizens should do X unless they have good reasons to do otherwise”. At the very least, those good reasons to do otherwise should be elicited explicitly (but they can, and do, change over time).
Take speed limits, for example. Probably we can all agree that driving at 100 mph in city centre is a terrible idea, so the law forbids it in basically every nation (elicited exception: you’re a police officer during an high speed chase). But the actual speed limits probably won’t let you drive at 100 mph anywhere, not even if you are the only driver along a giant straight road in Nebraska with perfect weather. If you still respect the official speed limits in these conditions, probably is because you don’t want to get a ticket from the police (or because you don’t trust too much your own driving abilities, but let’s just ignore this case for now). Legal positivism applied to speed limits is John Nestor, and I would guess that even the large majority of legal officers don’t drive like Nestor, or he wouldn’t have one-third of his Wikipedia entry dedicated to this. Even in this case, I think that letting an occasional Nestor cause traffic jam is still a better idea than just writing down “drive at whatever speed you judge appropriate”.
On a more general level, I think that a simple fear to get punishment from the upper level of the bureaucracy should be enough to justify the simplest form of legal positivism. Stick to the letter of the law, and no one could formally accuse you of any infraction.
The legal system must above all be predictable, and you’ll have a very hard time being predictable if your legal rules are written like “citizens should do X unless they have good reasons to do otherwise”. At the very least, those good reasons to do otherwise should be elicited explicitly (but they can, and do, change over time).
Take speed limits, for example. Probably we can all agree that driving at 100 mph in city centre is a terrible idea, so the law forbids it in basically every nation (elicited exception: you’re a police officer during an high speed chase). But the actual speed limits probably won’t let you drive at 100 mph anywhere, not even if you are the only driver along a giant straight road in Nebraska with perfect weather. If you still respect the official speed limits in these conditions, probably is because you don’t want to get a ticket from the police (or because you don’t trust too much your own driving abilities, but let’s just ignore this case for now). Legal positivism applied to speed limits is John Nestor, and I would guess that even the large majority of legal officers don’t drive like Nestor, or he wouldn’t have one-third of his Wikipedia entry dedicated to this. Even in this case, I think that letting an occasional Nestor cause traffic jam is still a better idea than just writing down “drive at whatever speed you judge appropriate”.
On a more general level, I think that a simple fear to get punishment from the upper level of the bureaucracy should be enough to justify the simplest form of legal positivism. Stick to the letter of the law, and no one could formally accuse you of any infraction.