Three members of a B.C. polygamist sect are to go on trial in B.C. Supreme Court Tuesday for allegedly taking underage girls across the U.S. border to become child brides.

James Marion Oler, Brandon James Blackmore and Emily Ruth Gail Crossfield all face one count of removing a child under 16 from Canada with the intent of facilitating an act of sexual interference or invitation to sexual touching.

Cross-border brides

Blackmore and Crossfield were husband and wife. They're accused of taking a 13-year-old identified as MMB across the border near Creston, B.C., in February 2004.

Oler is the former leader of one of two polygamist factions in Bountiful, a tiny community nestled in the mountains of the Creston Valley.

The trial will be held in Cranbrook, about 100 kilometres northeast of Creston.

Winston Blackmore, pictured, and James Marion Oler are charged with practising polygamy as part of separate court proceedings. (CBC)

Oler is accused of taking a child identified as CEO across the border to marry in June 2004.

Both Bountiful groups have their roots in the Fundamentalist Church of Jesus Christ of Latter Day Saints (FLDS).

Oler and the leader of the other Bountiful sect, Winston Kaye Blackmore, are also charged with practising polygamy as part of a separate indictment which will be tried at a later point. According to a sworn statement, Oler has four wives.

Brandon James Blackmore is Winston Blackmore's older brother.

'I will just be their boy trouble'

Details about marriages involving Canadian teen brides emerged in 2011 during proceedings in B.C. Supreme Court to determine the constitutionality of outlawing polygamy.

The judge in that case was asked to balance the harms of marrying multiple partners against the rights of Canadians to practice freedom of religion and lifestyle.

Records seized from imprisoned former FLDS leader Warren Jeffs are likely to be introduced into evidence at the trial of three B.C. residents accused of taking girls across the U.S. border to become child brides.

The court received an affidavit from Nick Hanna, a Texas Ranger who was one of the officers to raid the FLDS Yearning for Zion Ranch in Eldorado, during an investigation into former FLDS leader Warren Jeffs.

They seized thousands of pages worth of marriage records and dictations by the 60-year-old who is now serving a life sentence for child sexual assault.

They include dictation in which Jeffs allegedly described his own wedding to a 13-year-old in March 2004.

"I am smiling. I rejoice in the Lord's will. These young girls have been given to me to be taught and trained how to come into the presence of God and help redeem Zion from their youngest years before they go through teenage doubting and fears and boy troubles," Jeffs allegedly said.

"I will just be their boy trouble and guide them right, the Lord help me."

'Sealed in celestial marriages'

According to the affidavit, Hanna was asked to provide FLDS records for the purpose of B.C. court proceedings relating to three 12 and 13-year-old girls reportedly "sealed in celestial marriages" to Jeffs in 2004 and 2005.

The records also allegedly contain details about numerous other marriages between men from Canada and FLDS members in the United States.

The court documents include dictations in which Jeffs allegedly describes receiving divine inspiration on how to transport girls from Canada to Texas in 2005.

Those included instructing one man to destroy his phones before crossing the border and carrying the teens in trailers so they "would not have to go to gentile places to use the restroom."

None of the allegations has been tested in court.