I don't know if it will take 30 years or 50, but my gut feeling is that "spirit of the law" is much much more tenuous than "letter of the law". Who knows if the US is metastable. Things have been going nuts with the legal system here but it is also 250 years old. Most european democracies are a much younger experiment (and france is on what, attempt #5? Maybe #6 if you count subsumption into the EU as an unrecognized, but fundamental change in political dynamics).
Maybe an expert in the history of "civil law" will chime in, but my guess is that the "spirit of the law" principle has been in the legal systems of continental Europe since ancient Rome.
Yes, particularly legal systems that derive from Roman law (France, Spain, Italy) rely more heavily on this concept than those that derive from English Common law.
There's a saying I've heard somewhere, in England everything is allowed unless it is prohibited, in Germany everything is prohibited unless it is allowed and in France everything is allowed even if it is prohibited.
I guess I should have been clear that I meant stability + a democratic/republican system that preserves civil liberties, not stability with respect to the continuity of governments in the absolute sense.
To add with common law systems, we also can completely ignore the law. The state can as well just because there are so many laws. So stupid laws like "you can't chain a donkey to a tree with a wheelbarrow" are often ignore because the culture has just changed significantly.
