“For decades, most state regulatory systems have operated on autopilot. Once a rule is adopted, it usually stays in force unless someone can marshal the time, political will, and technical knowledge to repeal it. That default favors regulatory accumulation. Agencies add rules to address new problems, implement new statutes, satisfy federal requirements, or respond to isolated incidents. But old rules rarely receive the same scrutiny. Over time, the regulatory code grows not because every rule remains necessary but because inertia protects what already exists.

Idaho broke that pattern. And that state’s example can teach a lesson to states all over the country.

Beginning in 2019, Idaho used two related mechanisms to reset and then review its entire administrative code. First, after the legislature did not enact the customary bill extending existing rules, Governor Brad Little directed agencies to republish only the subset of rules considered necessary to that agency. But crucially, these were retained as temporary rules.

Second, the governor issued Executive Order 2020-01,[1] which required executive-branch agencies to review and generally repeal and replace each remaining rule chapter on a staggered five-year schedule covering 2021–25, with a legislative review concluding in 2026.

This issue brief refers to these combined steps as Zero-Based Regulation (ZBR). Through these two steps, instead of asking only which regulations should be repealed, Idaho required agencies to justify which provisions should remain. That shift produced one of the most dramatic state-level regulatory reductions in recent memory: by the end of the ZBR cycle on July 1, 2026, Idaho had eliminated roughly half (49.1%) of its regulatory code. Regulatory volume fell in each of the eight annual code publications from 2019 to 2026 under ZBR.”

From Manhattan Institute.