Responding via e-mail and under comments to my question, Tim Duffy, Executive Director of the Rhode Island Association of School Committees, kindly explains the preamble to and basis of the Portsmouth School Committee’ lawsuit against the NEA-Portsmouth.

The Portsmouth school committee implemented a new personnel policy that based teacher assignments on qualifications as opposed to seniority; the union contended that the policy needed to be negotiated and filed a complaint with the labor relations board.
The committee is seeking injunctive relief and a declaratory judgment that:
1. They have a management responsibility to students to assign teachers based on student need.
2. That case law grants this right and therefore the labor board lacks jurisdiction.

(Come to think of it, does the Labor Board have ultimate jurisdiction over anything? What percentage of the complaints filed with the Labor Board have ended at that body?)