The state Supreme Court on Friday turned down an appeal by Florida Power & Light in a case about whether the utility could be required to install underground transmission lines as part of a nuclear-power project in Miami-Dade County.

Justices, as is common, did not explain their reasons for declining to take up the case. But the decision was a victory for local governments, including the city of Miami, that have tangled with FPL about the transmission-line issue and local development regulations.