Lawyers for two men who may use same sex-marriage as part of their defence for polygamy asked BC Supreme Court to quash the charges Sep 3.
Winston Blackmore, 52, is charged with marrying 20 women, and James Oler, 44, is accused of marrying two women.
Blackmore's lawyer, Bruce Elwood, told a BC Supreme Court judge Thursday that former BC Attorney General Wally Oppal had no authority to appoint the special prosecutor who recommended charges against the men.
As such, he argued, the charges and arrests were invalid.
Previously, Elwood told Justice Sunni Stromberg-Stein that Oppal went "prosecutor shopping" in order to lay charges against the men.
Elwood said Oppal rejected two independent special prosecutors' recommendations that charges not be laid.
The first special prosecutor, Richard Peck, had suggested a constitutional reference be sought before the possibility of laying charges.
Charges were laid after a third prosecutor, Terry Robertson, agreed with Oppal.
Elwood had asked the judge to order the government fund his client's defence if the charges are not dropped.
Oler's lawyer, Bob Wickett said he expected Stromberg-Stein to reserve decision on the application to quash the charges.
Blackmore was not in court, and Oler had no comment on the proceedings.
Oler and Blackmore were arrested in January.
They are rival religious leaders in the polygamous Fundamentalist Church of Jesus Christ of Latter-day Saints community of Bountiful in southeastern BC.
After his arrest, Blackmore claimed there are tens of thousands of polygamists across Canada. He maintains his religious sect is being singled out, disregarding his right to religious freedom.
The charges carry a maximum penalty of five years in prison.
Elwood said the case will be a test of Canada's polygamy laws, and is expected to wind up in the Supreme Court of Canada.
Blackmore's former lawyer, Blair Suffredine, previously suggested the defence could invoke the right to same-sex marriage in Canada. Canada's Parliament extended full marriage rights to same-sex couples in 2005.
Oppal, who was not re-elected in BC's last provincial election, held that some legal experts believe polygamy charges won't withstand a constitutional challenge in Canada over the issue of freedom of religion.
Oppal said at the time of the arrest that he believes polygamy is an offence in law, and that the case is about the exploitation of women.
And, he added, if someone says that's contrary to their religion, then the issue is now up to the courts.
Blackmore and Oler were arrested at their Bountiful, BC commune Jan 7.
Blackmore was long known as "the Bishop of Bountiful."
He runs an independent group of about 400 people in the hamlet only hundreds of metres from the US border.
He once ran the Canadian wing of the Utah-based FLDS but was ejected by Prophet Warren Jeffs.
Oler is the bishop of Bountiful's FLDS community and is one of Jeffs' followers, who was convicted by a Utah jury in 2007 on two counts of first-degree felony rape as an accomplice.
FLDS members practice polygamy in arranged marriages, a tradition tied to the early theology of the Mormon church. The mainstream church renounced polygamy in 1890, but several fundamentalist groups left the main church in order to continue the practice.