The fight over restarting the nuclear industry is moving to the courts, where power companies face the risk of further delays in firing up idled reactors if judges side with local residents worried about nuclear safety.

Four reactors owned by two utilities cleared regulatory safety checks in recent months, opening up the possibility of ending more than a year without atomic power in Japan, the first such spell in the four decades it has been using nuclear energy.

And while ruling politicians and Japan's bureaucracy are pushing for restarts, the judiciary — which typically sided with power companies before the 2011 Fukushima nuclear disaster — may be shifting its attitude.