The lawsuit, filed Thursday, alleges that the Rev. Luis A. Bonilla Margarito carried on a sexual relationship with the teen while he was the chaplain of Reading Central Catholic High School and she was a senior there.
The girl's parents became suspicious and installed a camera in their basement, where Bonilla and the teen were spending large amounts of time. The camera recorded the couple having sex in November 2009, after she had graduated, according to the suit.
Her parents took the video to the Diocese of Allentown, which removed Bonilla from his dual posts as chaplain and pastor of St. Joseph Church in Reading after he acknowledged an "inappropriate relationship" with the teen, according to a diocesan news release.
Bonilla was sent to a treatment facility, but "continued to have intimate contact with (the teen) during this time period and ultimately impregnated her," the suit said. She recently gave birth to a girl.
Bonilla, 41, has since left the treatment facility and now lives in Norristown. He could not immediately be reached for comment.
"He has no assignment and he has not functioned as a priest since November," diocesan spokesman Matt Kerr said Friday.
The lawsuit seeks punitive damages for breach of fiduciary duty, infliction of emotional distress and gross negligence. It names as defendants Bonilla, the diocese, the high school, Allentown Bishop John O. Barres, and former Bishop Edward Cullen.
The suit was first reported by the Reading Eagle newspaper.