Carlo Dallas Vedova, Knox's Italian lawyer, told ABC News Tuesday her defense team had filed an appeal in Perugia, Italy.
While Knox, 24, who lives in Washington state, was acquitted Oct. 3 in the slaying of Meredith Kercher, her British roommate, she was resentenced for slander for accusing bar owner Patrick Lumumba of being involved in Kercher's killing.
The appeals court ordered that she serve three years in prison, up from two, for slander but she was released from prison because she had already spent four years in Italian jails. She had been sentenced to 26 years. ABC said during her initial lengthy interrogation -- which lasted 50 hours -- Knox indicated to police Lumumba was at the crime scene the night of Kercher's death.
"Amanda was confused, stressed and pressured," attorney Dalla Vedova said. "She has been acquitted of murder, and she should be acquitted of slander."
Italy's Supreme Court ruled Knox's statement against Lumumba inadmissible and he was awarded damages, ABC News said.