The polygamist family portrayed on the TLC reality show "Sister Wives" said all along its main goal in going on national television was to gain public acceptance of its lifestyle.
Now family patriarch Kody Brown, his four wives and 16 children and stepchildren are moving from the court of public opinion to the court of law, arguing that criminalizing their lifestyle is unconstitutional.
"This is not an effort to endorse polygamy," said Jonathon Turley, the family's attorney. "What it is is an effort to reaffirm privacy."
The law banning polygamy dates back to a Supreme Court decision in 1879 that called it "an offense against society." The court said it is not protected by religious freedom, just as "human sacrifice" is not protected.
On Wednesday, the Browns are expected to file a federal lawsuit to challenge the polygamy law in their home state of Utah, where they came under investigation for violating the state law that prohibits polygamy.
Turley, who is not a polygamist, is making the case that a lifestyle many Americans abhor should actually be tolerated.
"Right now we live in a bizarre situation where everyone agrees that you can have multiple lovers, you can have children by those lovers, you can even have adulterous lovers and you're protected as a citizen of the United States," Turley told ABC News. "But the minute you tell them privately that you view them as your spiritual spouses the state comes in and prosecutes you."
Susan Ray Schmidt, author of the book "Favorite Wife: Escape from Polygamy," told ABC News there is no such thing as a healthy relationship in a polygamist lifestyle.
"There is not a single polygamist family out there where the women are truly happy inside," said Schmidt.
Other critics of polygamy argue that the government does have a right to ban polygamy, pointing to scandals involving child abuse and child brides among "fundamentalist" Mormons. Turley counters that there have been no allegations of abuse against the Browns and that there is plenty of child abuse and spousal abuse among monogamous couples.
"We didn't want this thing hanging over us," Brown, a salesman, told ABC News' Dan Harris on "Nightline" last March. "We went to Vegas with hopes of having a good life, preserving the family. ... We never did anything here at all to be rebellious, to challenge the statutes of the law or anything like that."
"We still have our family," Robyn, Brown's fourth wife, said. "That's all it boils down to."
Police in Lehi, Utah, launched an investigation into the Brown family's lifestyle last September for a possible charge of bigamy after TLC initially announced the show "Sister Wives." Bigamy is a third-degree felony in Utah and punishable by up to five years in prison.
The state law reads: "A person is guilty of bigamy when, knowing he has a husband or wife or knowing the other person has a husband or wife, the person purports to marry another person or cohabits with another person."
Kody Brown is legally married to one woman, Meri, but also calls the other three women his spouses.
While the Mormon family could still face prosecution, a representative from the Utah County Attorney's Office said it still has not filed criminal charges against the Browns, but a decision could come in weeks.
Kody Brown and all four of his wives told "Nightline," on the eve of their series' second season March 13 premier, that they had mixed feelings about putting themselves and their 16 children in the spotlight but had tried to maintain a positive attitude.
"We did this to open up the minds of America, and we did this to show our functional family," Robyn Brown said. "We just deal with it. We live with it."
Another reason for coming forward as polygamists, they said, was the opportunity to give their children a different life from the one some of the wives had experienced.
"I grew up in a polygamist family, and I felt fear," said Christine, Brown's third wife. "We were taught that we couldn't talk about our lifestyle ... and we were cautious of the police, but we haven't raised our kids that way. We haven't wanted our children to feel fear like that. ... We just wanted something different for our kids."
As reported by the New York Times, the Browns' purported lawsuit does not demand that states recognize polygamous marriage but asks that federal courts tell states they cannot punish polygamists for their "intimate behavior" so long as they are not breaking other laws, such as child abuse or incest.
Challenge to the Criminalization of Polygamy
The Browns are members of the Apostolic United Brethren Church, a fundamentalist break from the Church of Jesus Christ of Latter-day Saints -- the Mormon church, which officially banned polygamy more than 100 years ago as Utah sought statehood.
In making their case, the Browns argue that making polygamous unions illegal violates the free exercise, establishment, free speech and freedom of association clauses of the First Amendment, and the due process and equal protection clauses of the 14th Amendment.
The Browns have faced no allegations of incest, child abuse or child brides, despite the inquiries into their lifestyle, something that could help their case in court.
"We believe that this case represents the strongest factual and legal basis for a challenge to the criminalization of polygamy ever filed in the courts," said the Brown's attorney, Jonathan Turley, a law professor at George Washington University.
A ruling in the Brown's favor would affect tens of thousands of people in polygamous families in the United States.
Since the show first aired, the Browns told "Nightline" they had received many positive reactions from people in their community and strangers who have reached out to them through other means, such as Facebook, but have also faced discrimination.
"My job, I absolutely loved," Meri Brown said. "When I came out as a polygamist, and you know, became public, I was fired. That being said, some of my friends who had no idea have been extremely supportive of me."
In the end, the Browns told ABC News, they were glad they had at least raised awareness about their lifestyle and shown that even though polygamists, they were a loving family.
"We started this so that we would hopefully open and create more tolerance in the world," Janelle Brown said. "I hope that's what we're accomplishing here."
ABC News' Lauren Effron contributed to this story.