Collective Bargaining Bumping Up Against No Child Left Behind Law

District leaders in Philadelphia, citing the federal No Child Left Behind Act, are pushing for significant cutbacks in teachers' seniority rights.

The proposal that principals be allowed to disregard seniority in most hiring decisions has outraged the teachers' union. For nearly 40 years, job openings for Philadelphia teachers—like those in many districts—have been filled primarily on that basis.

The unresolved dispute in the nation's eighth-largest school system illustrates an ongoing debate about whether districts will need to seek changes in collective bargaining agreements to comply with the No...