Trent Thorburn asks for lighter sentence

Trent Thorburn's four-year jail term for incest and perjury relating to the case of his foster sister Tiahleigh Palmer should be slashed because his time in solitary confinement was not given enough weight, a court has heard.

Thorburn was sentenced last month after pleading guilty to four charges, including perjury, and admitting he'd had a sexual encounter with 12-year-old Tiahleigh in the days before her alleged murder in October 2015.

Barrister Rob East has argued in Queensland's Court of Appeal that Thorburn's 359 days in pre-sentence custody was spent largely in the "dehumanising" environment of solitary confinement and should have led to a lighter overall sentence.