Fields, who was named the 2012 Big 12 Defensive Player of the Year as a freshman at TCU, is set to enroll at Louisville on Aug. 4, according to Petrino. The Cardinals open preseason on Aug. 6.
"We've established that he's going to have to do everything right when he's on campus with us," Petrino said during an appearance Monday at ESPN. "We have some standards that are set for him, and he's going to have to abide by those standards."
Fields, from Fort Worth, Texas, was charged in July 2014 in a domestic incident concerning his ex-girlfriend, who accused him of pointing a gun at her and punching her in the face. Fields was dismissed from TCU after he was charged with misdemeanor assault causing bodily injury. The case was dismissed last month after Fields completed an anger management course.
"We're privy to all the information," Petrino said. "We understand all the information that was out there. Knowing that, we believe we did the right thing in giving him a second chance."
Fields led the Horned Frogs with 18 ½ tackles for loss and 10 sacks in 2012, but then he played in only three games in 2013 because of a foot injury. He spent last season at Trinity Valley Community College in Athens, Texas, and was named the country's No. 4 juco prospect by ESPN Recruiting.
"Fields has experience," Petrino said. "He's an edge rusher, which is something we lost last year. He's going to have to show that he's a quick learner and understands the defense in a quick time."