BAD character evidence was wrongly introduced to bolster a weak case against a man found guilty of raping an unconscious woman at his Derry flat, the Court of Appeal has heard.

Disclosing details about a previous sexual assault at Shaun Hegarty's trial rendered his conviction unsafe, defence lawyers claimed.

Hegarty (30) is serving a 20-year prison sentence for carrying out the latest attack in April 2019.

The woman was discovered collapsed on the city's Northland Road and told police she had a few drinks at Hegarty's apartment and remembered little apart from waking up on a mattress on a concrete floor.

She said a rope was put around her neck at one stage. She spent a week in hospital for treatment to a traumatic brain injury and other wounds.

Hegarty of Balliniska Heights, claimed they had engaged in consensual "rough sex" and she hurt herself by walking into a door.

Following a trial at Derry Crown Court, he was found guilty of raping, attempting to choke and assaulting the woman.

Jurors heard how he was previously jailed for rape in 2010.

Appealing the latest conviction, defence counsel Brian McCartney QC argued the complainant's credibility was undermined by inconsistencies in her version of events and no stupefying substances were discovered at Hegarty's.

Counsel challenged the decision to allow bad character evidence at the trial and the timing of its introduction, claiming there were significant circumstantial and factual differences between two alleged offences committed nine years apart.

A prosecution barrister insisted the extent of the woman's serious injuries does not fit in with Hegarty's account and contended the trial judge was entitled to admit bad character in a case where the jury was advised of both similarities and dissimilarities between the two incidents.

Acknowledging the complainant had initially lied about where she met Hegarty, the barrister said "she gave an account of what she said happened to her, it's inconsistent with the account the accused gave".

Reserving judgment, Lady Chief Justice Dame Siobhan Keegan pledged: "We will provide a ruling as soon as we can".