Pax on NZ1 and NZ2 AKL LHR via LAX and return - do have to clear US Immigration - so any felons will not be allowed to board.
AC used to fly SYD YVR via HNL and return and this was often an issue on these flights too.
This is one of the reason why NZ has gone with AKL LHR via HKG as the pax just found getting off the plane in LAX lining up being processed and then going back thru security just to sit in a transit lounge a total pita