A state appeals court upheld a lower court ruling that a law designed to give Mayor Antonio Villaraigosa of Los Angeles partial authority over schools is unconstitutional. The ruling was a second legal blow to the law, which sought to shift some powers from the Los Angeles Unified School District’s elected seven-member board to the mayor and a new council of more than two dozen other mayors. “The citizens of Los Angeles have the constitutional right to decide whether their school board is to be appointed or elected,” the appeals court wrote in its decision.