Blackmore is accused of marrying 24 women. Oler is accused of having four wives.
Suffredine said in court that evidence against Blackmore was collected from 1990 to 2011, a period when the constitutionality of Canada's laws prohibiting polygamy was unclear. The law was upheld in 2011.
Following years of legal wrangling, a criminal trial for Blackmore and Oler began last month, more than 25 years after Royal Canadian Mounted Police first began investigating allegations that residents of the isolated, religious community were practicing plural or "celestial" marriage in the early 1990s.
British Columbia Supreme Court Justice Sheri Ann Donegan ruled Monday to allow into evidence statements made by Oler to police about his wives.
Investigators met with Oler in October 2005 to get his permission to interview the women during an investigation into alleged sexual exploitation.
The court has heard that Oler admitted to having three wives and said he would set up a time for police to conduct interviews. Since it was a general inquiry and not a formal police interview, it was not recorded.
Donegan ruled that Oler knew he was under police scrutiny, but that the statements about his wives were made voluntarily outside of the scope of the sexual exploitation investigation.