The leader of a US polygamist sect forced a 14-year-old girl to marry her older cousin, despite her protests, prosecutors say.
Mr Jeffs was a fugitive for nearly two years before his arrest in Las Vegas
Warren Jeffs, 51, is on trial accused on two counts of being an accomplice to rape. He denies the charges.
He has been in custody since August 2006, when he was arrested in Nevada after 15 months on the run.
Mr Jeffs leads the Fundamentalist Church of Jesus Christ of Latter Day Saints (FLDS) in Arizona and Utah.
The 10,000-strong sect split from the Mormon Church more than a century ago after the latter renounced polygamy.
The jury, in St George, Utah, has been asked to decide whether Mr Jeffs "intentionally, knowingly or recklessly" encouraged the girl to have sex against her will.
Sentences for the offence range from five years in jail to a life term.
Prosecutor Brock Belnap told jurors the girl would testify that she "got down on her knees and begged" Mr Jeffs to postpone the wedding, saying she was too young and did not want to marry her cousin.
"What Warren Jeffs told her is: 'Your heart is in the wrong place. This is your mission and duty to do.'"
But lawyers for Mr Jeffs questioned what really happened between the girl and her husband, and the extent to which Mr Jeff influenced it.
"Was she really raped? That's the core question," Tara Isaacson said in her opening statement for the defence.
"What did Warren Jeffs have to do with what was going on in the bedroom? Did he even know she was forced to have sex?"
Ms Isaacson also told the jury, of seven women and five men, that the girl's age was not an issue.
The sect leader went into hiding after being charged in Arizona with sexual misconduct for allegedly arranging marriages between minors and older men.
He was on the FBI's Ten Most Wanted list at the time of his arrest, which came when he was pulled over during a routine check by traffic police near Las Vegas.
The trial is being held in Utah as the charges he faces in that state are more serious than those in Arizona.
Mr Jeffs, who is reputed to have 70 wives, took over the leadership of the church after his father Rulon died in 2002.
The sect dominates the towns of Colorado City, in Arizona, and Hildale, Utah, less than a mile away. A compound in Eldorado, Texas, is also home to a growing community.
Members believe a man must marry at least three wives in order to ascend to heaven. Women are taught that their path to heaven depends on being subservient to their husband.
Polygamy is illegal in the US, but the authorities have reportedly been reluctant to confront the FLDS for fear of sparking a tragedy similar to the 1993 siege of the Branch Davidian sect in Waco, Texas, which led to the deaths of about 80 members.
However, observers say the church is coming under increasing pressure from authorities in Utah and Arizona.