A statewide organization that counts both the Boston and State Police departments as members is backing BPD in the agencies’ long-standing turf war to patrol the Seaport District, arguing that the state department’s claim to sole jurisdiction is an outdated model of policing.

In a letter to Governor Charlie Baker’s public safety secretary, the Massachusetts Major City Chiefs argues that Boston police should be given shared authority in the rapidly changing area because it is “in the best, most suitable position to provide the optimum level of policing services.”

“As local police chiefs, the concept of so-called ‘sole jurisdiction’ is a policing dictum of the past,” reads the three-page letter, signed by the organization’s officers and addressed to Secretary Daniel Bennett.

“It lends itself to significant delays in the delivery of public safety responses, leads to miscommunication/misunderstanding, increased frustration, and endangers overall officer safety and all to the detriment of the residents who are entitled to the highest quality of policing services available.”