Sleeping sex attack.
But a psychiatrist told a court in Darwin, Australia, that Spencer could have suffered "sexsomnia".
Spencer, 48, insists he has no recollection of the event at his home at Nhulunbuy, in remote Arnhem Land, last June.
Giving evidence by video link, Dr Lester Walton told the court memory loss was "a hallmark" of sleepwalkers.
He said: "It's reasonably well established that sexual behaviour can form part and parcel of somnambulism."
The trial continues.