Environmental regulation stringency — emissions caps, standards, phase-out mandates, carbon pricing, renewable portfolio standards.
General government spending as share of GDP, excluding transfers already captured under fiscal.transfer_expansion to avoid double-counting.
Estonia introduced a motor vehicle tax from 2025, combining an annual tax liability for registered vehicles with a registration fee for first registration or ownership changes. The tax base uses vehicle attributes such as emissions, mass, age, and engine type, creating a new recurring charge on car ownership while steering households and firms toward lower-emission vehicles.
Per invariant 3, reforms are scored by what they did on each channel-separated axis, not by the party that enacted them. This fingerprint is how the policy-match engine finds historical analogues.
Explicit links are curated by the author. Inferred links are hypotheses in the library that test the same axes this policy moved — the framework's answer to "what does the data say about a policy like this?".
Ranked by axis-fingerprint overlap with this policy. Direction match bolded — those are the closest historical analogues. Shape of the match is what drives policy-outcome comparison, not the country or party label.