The sunset clause for the constitution and amendments should probably be on the order of decades; those aren't individual actions but wide ranging codes, with a VERY HIGH BARRIER of entry (and they should have just as high a bar to clear for maintenance). They should still be reviewed, curated and maintained over time to keep them matched to contemporary language. The changes in language would also allow for re-review of case law and other methods of defining what laws mean. That would also be a strong reason for maintaining the language as is if it currently works.

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Also, like DHCP leases, for such important items you'd want multiple review chances. E.G. If it's a 100 year expiration, review at 30 left, 15 left, 10 and 5+ left possible to review at any time.