Kim McGuinness has warned that reducing England and Wales's 43 territorial police forces to a small number of regional mega-forces could weaken local accountability.
The North East Mayor intervened after Metropolitan Police Commissioner Sir Mark Rowley argued that the present structure should be replaced by eight to ten larger forces. The Government has not adopted that number and an independent review has yet to report.
McGuinness said a locally accountable force was a cornerstone of the criminal justice system and cautioned against undoing a model that has underpinned British policing for generations.
She also rejected the idea that the Metropolitan Police should dictate how northern forces are organised, saying the Met was not in a position to preach to them.
The Government's policing white paper has already committed to a model with fewer, larger forces alongside new local policing areas. The review is examining the optimum number, boundaries, governance and possible pathfinder mergers.
The dispute now centres on scale and accountability rather than whether structural reform will happen. McGuinness's intervention presses ministers to ensure that any merger programme preserves local priorities, budgets and democratic oversight.
