Gene Gibson, who is from the remote desert community of Kiwirrkurra and speaks a dialect, is serving seven-and-a-half years behind bars for fatally striking Josh Warneke from behind as he walked home from a night out in Broome in 2010.
A series of flawed police interviews more than two years later were deemed inadmissible, forcing prosecutors to drop a murder charge and accept Gibson's guilty plea to manslaughter.
Gibson's conviction was appealed on the basis he suffered a miscarriage of justice because he did not have the cognitive ability or language skills to understand what was happening, with the 25-year-old claiming he gave a false confession.
His appeal hearing concluded in the WA Court of Appeal on Thursday, when the state told the full bench of three judges it was open to a verdict in Gibson's favour and an acquittal without a re-trial.
The judges reserved their decision.