State Preemption of Local Zoning in Maine
How Maine state law overrides local zoning ordinances. ADU preemption, lot split preemption, and impact on city-level regulations.
What Is State Preemption?
State preemption occurs when a state law overrides local government ordinances in a specific area. In land use, preemption means a city or county cannot adopt zoning rules that are more restrictive than the state standard. If a city tries to prohibit something the state law permits, the state law wins.
Maine actively uses preemption in housing law. The state has enacted legislation that prohibits local governments from blocking certain types of housing development — most notably accessory dwelling units (ADUs) and lot splits.
ADU Preemption
Maine LD 2003 — An Act To Implement Certain Recommendations of the Commission To Increase Housing Opportunities in Maine by Studying Zoning and Land Use Restrictions
This law preempts local ordinances — cities cannot impose rules stricter than the state ADU standard. Effective 2022-07-01.
What local governments cannot restrict:
- ADUs must be permitted as of right — no discretionary approval or public hearing required · Source
Source: Maine LD 2003 — An Act To Implement Certain Recommendations of the Commission To Increase Housing Opportunities in Maine by Studying Zoning and Land Use Restrictions. Last verified April 5, 2026. View source