Kody Brown on Friday said keeping polygamy a crime makes polygamous families afraid to call ambulances or social services that can help them.
"Stop prosecuting consenting adults," he said.
"I want my right to live my life as a consenting adult," said Meri Brown.
A film crew followed the Browns on Friday as they arrived at City Creek Park before leading about 100 people — polygamists, their children and supporters — up State Street to the Capitol.
There, the crowd grew to about 200, though some people opposed to polygamy were sprinkled among the polygamists; a film crew for "Escaping Polygamy," a reality show about people fleeing abuse in polygamous sects, was on hand. Supporters of polygamy chanted, "Families, not felons" until speakers addressed them.
Christine Brown was one of the people who went to a podium on the Capitol's south steps and spoke into a microphone.
She was raised in a loving family, she said, but one that taught the children to be afraid of the outside world for fear that police would enter the home and take away the men and children. She said children being abused in polygamous homes are still afraid.
"We need to change these laws to eliminate that fear," Christine Brown said.
Those who opposed polygamy and want legislators to pass a new bill addressing it talked about children and abuses Friday, too.
Pam Jenson, who has worked with people who have left polygamous families, said polygamy should remain a felony because it is harmful to women and children — an assertion the Utah attorney general's office made in opposing the Browns' lawsuit. She said HB99 will provide a "safe harbor" for people leaving such households.
"There's still religious coercion to stay" in polygamy, Jenson said.
HB99 passed a House of Representatives committee last week and is likely to be debated this week by the full body. The bill would amend the definition of bigamy to say someone is guilty if he or she "purports" to marry two or more people and cohabits with them. Current state law requires one or the other. Polygamy would remain a felony punishable by up to five years in prison, but those penalties can increase if polygamy is prosecuted in conjunction with violent crimes, human smuggling or fraud.
The bill also would permit amnesty for people leaving abusive polygamous relationships, though polygamists say it would create witnesses against others who remain in the plural marriage.
Prosecutors across the state have declined to pursue cases unless there's underage marriage, abuse or fraud in the households. Utah's polygamists would like polygamy to be decriminalized, but first they want to defeat HB99.
The first season of "Sister Wives" showed the family living in Lehi, but when police there began an investigation, the Browns moved to the Las Vegas area.