You're right that individuals do have to interpret the law, and choose their behaviour accordingly. AFAIK, it's only in the last hundred years or so that we've started to recognise human rights having precedence over a single nation's law, which makes it "legal" for individuals to act contrary to their nation's laws.

That recognition does make it easier (than it was) to counter, but there are still challenges, and they're unlikely to disappear soon.