Paul Edward Buckley, 24, has pleaded not guilty in the ACT Supreme Court to allegations he sexually assaulted the woman after a formal dinner for cadets in April last year.

The woman said she thought her husband had returned to their Royal Military College home when she heard the door open the next morning. She said there were footsteps on the stairs before a man entered the darkened ground floor lounge room where she had been asleep on the couch.

The court heard Buckley did not say a word, kissed and caressed the woman, pulled her pants down and then performed a number of sexual acts on her.

The woman said she became suspicious the man was not her husband and turned on the light to see Buckley as she chased him from the house. She reported the incident and Buckley was arrested about 5am.

The defendant entered the witness box on the third day of the trial to tell jurors he had been so drunk he had no memory of the alleged events.

But Buckley said his drunkeness meant he could not dispute he was in the house and performed the sexual acts as the DNA evidence suggested.

He denied trying to use his level of intoxication to avoid questions, arguing recall of the alleged incident would be easier on his family.

The court heard he had no sexual interest in the woman and the pair had not flirted in the time they had known each other.

In final submissions, the Crown urged jurors to return a verdict of guilty, arguing Buckley had gone to the home with ''sex in his mind'' and had been reckless as to whether the woman consented.

The prosecutor said the defendant's evidence had been unreliable and self-minimising, attempting to use intoxication and memory loss to play down his actions.

But defence barrister Ken Archer said his client's lack of recall were not convenient, as it meant he could not challenge the evidence before the court.

Mr Archer said drunkenly stomping through the house before entering the lounge room were not the actions of a man trying to misrepresent himself.

He told jurors identity was the main issue in the case and cast doubt on the woman's claims she mistook the defendant for her husband despite their close proximity.

Mr Archer argued the woman, from the witness box, had told jurors she thought the man entering the room was the defendant but wanted it to be her husband.

He said the woman always knew it was Buckley and his client had left immediately after she withdrew her consent.

Justice John Nield will direct the jurors and send them out to deliberate a verdict on Thursday morning.