Warren Jeffs appears in a Las Vegas courtroom in August 2006. (Laura Rauch/Associated Press)

The Utah Supreme Court on Tuesday reversed the convictions of polygamist leader Warren Jeffs and ordered a new trial, saying a jury received incorrect instructions before considering his role in the 2001 nuptials of a 14-year-old girl to her 19-year-old cousin.

Jeffs, 54, was convicted in 2007 of two counts of first-degree felony rape as an accomplice. He is serving two consecutive terms of five years to life in the Utah State Prison.

Jeffs is head of the Fundamentalist Church of Jesus Christ of Latter Day Saints. The group, based on the Utah-Arizona state line, practises polygamy in marriages arranged by church leaders.

Jeffs performed the religious marriage of Elissa Wall and Allen Steed in a Caliente, Nev., motel and later counselled Wall to be obedient and give her "mind, body and soul" to her husband in an effort to make an unhappy marriage work.

During the trial and later in her book, Stolen Innocence, Wall said she objected to the marriage and was forced into sexual relations with her husband.

Errors made

In its ruling Tuesday, the court agreed with defence attorneys who argued that jurors should not have been told to decide whether Wall's marital relations were consensual based on Jeffs' actions and his role as her religious leader. That essentially equates Jeffs with Steed — the person who allegedly has had nonconsensual sex.

Justices said prosecutors were wrong to make that leap.

"Only after there is a determination that an offence has been committed can the law impose liability on another party who 'solicited, request, commanded, encouraged or intentionally aided' in the commission of that offence," the court's opinion states.

Steed was charged with rape the day after Jeffs' September 2007 conviction, but the case has languished and it's unclear how it might now proceed.

Under state law, the parties in the case now have 14 days to ask for a re-hearing of the case before the Utah Supreme Court.

Also Tuesday, Jeffs was scheduled to appear in 3rd District Court so a judge can ask him to sign a warrant seeking his extradition to Texas to face criminal charges there.

Texas authorities used family records gathered during a 2008 raid on a church ranch near Eldorado to charge Jeffs with bigamy, sexual assault of a child and aggravated assault. The charges allege marriages between Jeffs and girls ages 17 and 15 in 2005.