Convicted killer and sex offender Phillip John Smith doesn't have the right to wear a wig in prison because it doesn't trigger laws surrounding rights to expression, the Court of Appeal has ruled.

The balding murderer - who was sentenced to life imprisonment for murder, paedophile offending, aggravated burglary and kidnapping in 1996 - won a case in the High Court in March last year against the Department of Corrections over its decision to take away his toupee.

Justice Edwin Wylie decided that wearing a wig was an act in exercise of his right to freedom of expression under the Bill of Rights Act.

Corrections took the case to the Court of Appeal.

In a decision released on Thursday, the three justices ruled that while Smith and others in prisons had the right to to be treated with humanity and with respect for their inherent dignity, wearing a wig did not not constitute "expression".

Wearing a wig for cultural or religious purposes was covered under the act, but the justices agreed with Corrections' assertion that "the wig was worn only to address Mr Smith's feelings of low self-esteem and self-confidence".

The justices decided that while Smith disliked being bald, wearing a wig did not attempt to convey meaning and it didn't engage the Act.

Smith was given an extra 33 months behind bars in 2016 after he flew to Brazil in November 2014.

He had been on temporary release from Spring Hill Prison and was able to leave the country using a passport issued under his birth name Traynor.