Mr Blackmore is said to acknowledge having an extensive family
Canadian police have charged the leaders of two rival religious sects in an isolated community with polygamy.
Winston Blackmore was alleged to have had 20 wives, while James Oler is accused of having had two. Canadian law outlaws the practice.
The two men lead fundamentalist breakaway Mormon sects in the town of Bountiful in British Columbia province.
Mainstream Mormons gave up polygamy in the 1890s so Utah could enter the US.
But the sect members believe that a man must have multiple wives to enter heaven.
The case was the first test of Canada's polygamy's laws, said British Columbia's attorney general, Wally Oppal.
"This has been a very complex issue," he said. "It's been with us for well over 20 years. The problem has always been the defence of religion has always been raised."
Mr Blackmore, 52, ran the Canadian branch of the Utah-based Fundamentalist Church of Jesus Christ of Latter-Day Saints (FLDS) until 2003 when he was removed by that group's leader, Warren Jeffs.
James Oler then took charge of Bountiful's FLDS congregation and Mr Blackmore went on to lead a rival group.
The Royal Canadian Mounted Police began investigating allegations of polygamy in the mountain community of Bountiful in 2005 and recommended charging the two men and possibly others.
Two subsequent reviews by special prosecutors said the government should get a court ruling on the constitutionality of Canada's Victorian-era polygamy laws before pressing charges - in case they were dismissed as going against freedom of religion laws.
A third special prosecutor, appointed by Mr Oppal in 2008, reviewed the cases and recommended pressing charges.
The issue is complicated by allegations of sexual abuse related to the marriage of underage girls to older men.
Former residents of Bountiful have alleged for more than 20 years that underage girls were being married to older men.
RCMP Sgt Tim Shields said the force's investigation showed some girls were married "well before the age of 18".
Mr Jeffs, the FLDS's American leader, is in jail in Arizona awaiting trial on charges of being an accomplice to sexual conduct with a minor linked to the sect's practice of marrying young girls to church leaders.
He has been convicted in Utah of being an accessory to rape for performing a wedding between a 19-year-old man and a 14-year-old girl.