In all, Kuhnhausen faces 14 counts eight third-degree felony counts of unlawful sexual contact with a 16- or 17-year-old and six class A misdemeanor counts of enticing a minor.
"It is alleged [the female victim] had multiple contacts with him where she engaged in sexual intercourse between October 2012 and January 2013," Salt Lake County District Attorney Sim Gill said Wednesday.
Prosecutors also allege that Kuhnhausen purchased a cell phone for the girl in January, which he used to send sexually explicit text messages to her.
The case continues to be under investigation, but Gill said that initially, it did not appear the alleged relationship between Kuhnhausen and the girl had developed in connection with the lawyer's professional capacity.
Calls to Kuhnhausen's law practice were referred to fellow Salt Lake City defense attorney Ron Yengich,who did not respond to a request for comment.
According to a probable cause statement, the victim told detectives that she was 16 years old when she first had sex with Kuhnhausen at his home in October 2012. During the ensuing four months, she said she and Kuhnhausen had intercourse seven more times.
Prosecutors say that after buying her the cell phone in January, Kuhnhausen sent "at least six text messages that asked her to engage in sexual activity with him."
Kuhnhausen, a 1977 graduate of the University of Utah Law School, was admitted to the Utah Bar Association in 1978.
He have been best been known for his involvement as a defense attorney for members of the John Singer family, in particular matriarch Vickie Singer, in the years following the polygamous clan's bombing of a Mormon chapel in Summit County in 1988. That bombing led to an armed standoff between the family and son-in-law Addam Swapp, during which Corrections Officer Fred House was shot and killed.
In addition to criminal defense work, Kuhnhausen handles family law and divorce cases.