A public school district cannot be held liable for a teacher's sexual abuse of a student because it had only suspicions and no actual knowledge of the abuse, said an appellate district court Monday in upholding the dismissal of a lawsuit.

According to Monday's ruling by the 7th U.S. Circuit Court of Appeals in Chicago in N.R. Doe et al. v. St. Francis School District, there initially was an exchange of text messages between a 26-year-old female teacher in the St. Francis, Wis., public school district and an anonymous 14-year-old eighth-grader.

In those messages, the teacher, Kelly Sweet, said she wanted the boy to be her boyfriend and invited him to her apartment.

He accepted the invitation, and when he arrived, the two spent 15 to 20 minutes “kissing and petting," said the ruling. This was followed by “sexually suggestive” text messages but no further physical contact.

Although the two agreed to keep their relationship a secret, the boy's mother discovered one or more of the messages and transferred him to a private school. Ms. Sweet subsequently pleaded guilty to fourth-degree sexual assault.

Meanwhile, Ms. Sweet's colleagues had complained to the school's principal that Ms. Sweet was text messaging during the day, and one teacher in particular was suspicious about an improper relationship between Ms. Sweet and the boy, according to the ruling.

The school's superintendent conducted an investigation, but none of the teachers had evidence to confirm their suspicions, and the district took no action at the time, according to the appellate court ruling. However, it terminated Ms. Sweet in August 2008 after the student's mother discovered the relationship through one or more text messages, according to the appellate court ruling.

The lawsuit filed in U.S. District Court in Milwaukee by the boy's parents charged the school district with violating Title IX of the federal Education Amendments Act of 1972, which prohibits sex discrimination in educational programs that receive federal financial assistance, and with negligent infliction of emotional distress under Wisconsin tort law.

In upholding the lower court ruling dismissing the charges, a three-judge panel of the 7th Circuit said “to know that someone suspects something is not to know the something and does not mean the something is obvious.”

After the teacher denied the improper relationship with the student, it is unclear what the superintendent could have done, said the ruling. The “danger must be known to the official, not known to someone else (in this case, merely suspected by someone else) and communicated to the official without proof,” said the appellate court.