SALT LAKE CITY — Bigamy charges will not be filed against the family featured in the TLC series "Sister Wives," the Utah County Attorney's Office announced Thursday.

In a motion to dismiss a lawsuit filed against him by the polygamous family, Utah County Attorney Jeffrey Buhman said his office has adopted a formal policy not to prosecute the practice of bigamy unless it occurs in conjunction with another crime or if a party to the marriage or relationship is under 18.

"The purpose of this policy is to prevent the future prosecution in Utah County of bigamist marriages entered into for religious reasons," Buhman wrote in a memorandum supporting his motion to dismiss.

"The criminal case against the Browns is now closed, and no charges will be filed against them for bigamy," unless new evidence is discovered that violates the county's bigamy policy, the county attorney wrote.

Kody Brown and his four wives, Meri, Janelle, Christine and Robyn, issued a statement Thursday, saying they're "delighted by the news that the prosecutors have formally declared that the investigation of our family is at an end."

"We have spent years under investigation and ultimately had to move from the state of Utah to protect our family and particularly our children," the statement continued. "The decision to create the new policy in light of our lawsuit is wonderful news for not just ourselves but the many thousands of members of plural families in Utah."

But attorneys for the Browns aren't dropping their legal challenge. In a statement on his blog, lead counsel Jonathan Turley said the lawsuit will continue.

"While I am pleased that the prosecutors are now promising to leave this family alone, the decision will not end our challenge to the state law," Turley wrote.

Attorneys for the Browns filed an 80-page motion and brief Thursday "challenging the anti-bigamy law on seven distinct constitutional and statutory grounds," he wrote.

"We look forward to arguing that motion before Judge (Clark) Waddoups in Salt Lake City," Turley wrote.

In February, a federal judge ruled there was sufficient evidence to allow the Browns to pursue a lawsuit against Buhman contesting the constitutionality of Utah's bigamy law.

In July 2011, the Browns brought a lawsuit against Gov. Gary Herbert, Attorney General Mark Shurtleff and Buhman, claiming that Utah's bigamy statute violates the family's constitutional rights to due process, equal protection, free exercise of religion, free speech and freedom of association.

Waddoups ruled that the Browns could only sue Buhman because his office made clear in media interviews that he intended to investigate and prosecute the Browns after the reality TV show "Sister Wives" debuted in September 2010.

Fearing prosecution, Brown moved his wives and 16 children from Lehi to Nevada in January 2011. In a court declaration written in October 2011, Janelle Brown said the family lives in fear in Nevada and has suffered financial and spiritual losses.

The family has repeatedly expressed its desire to return to Utah once there is no longer a threat of prosecution.

In court documents filed Thursday, Buhman denies making promises or threats to prosecute the Brown family. "I never stated publicly that I would or would not prosecute the Browns," he wrote, "though I'm aware others in my office may have responded to the press to that effect."

Because the county has determined no charges will be filed against the Browns, Buhman has asked the court to dismiss the lawsuit against him.

The Utah County Attorney's Office originally got involved in the investigation in October 2010, after receiving a report from the Lehi Police Department about "Sister Wives."

In the court documents, Buhman said the report alleging bigamy was the first to be submitted to the Utah County Attorney's Office since he took office in January 2007.

At that time, the attorney's office "did not have a formal policy regarding the prosecution of bigamy," according to court documents. In addition, no one in the office had any recollection of Utah County prosecuting anyone for the practice of bigamy, except in the case of marriage fraud or failure to obtain a divorce prior to remarrying, Buhman wrote.

Utah County's new policy is similar to that of the Utah Attorney General's Office.

"This policy is not intended to just apply to the Browns," Buhman wrote in the memorandum, "but is meant to stand as a permanent policy of the Utah County Attorney's Office to be applied equally to anyone engaged in the practice of polygamy."

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