A court has rejected a bid by labor groups to block the Industrial Welfare Commission’s recent changes to California’s overtime laws, set to take effect January 1. Unless overturned by a higher court, this latest development clears the way for overtime to be required only after 40 hours in a week rather than after eight hours in a day. A measure to undo the commission’s action is winding its way through Sacramento. It is likely to pass, but faces certain veto by Governor Wilson.