In 2005, Jairus went to play football for the Duck’s at the University of Oregon. He red-shirted his freshman year, but by 2006 he was playing and showing promising talent. That year Jairus was named to the freshman All-American second-team by the Sporting News and was the PAC-10 co-freshman Player of the Year. Jairus played the last 11 games of the season at cornerback, recording 56 tackles and five interceptions. The following year Jairus started all 13 games for Oregon, recording 64 tackles, a sack, and a conference leading seven interceptions, which led to him being named All-PAC 10 conference honorable mention as a sophomore. During his junior season, his last at Oregon, Jairus was an All-Pac 10 first-team selection as well as the Defensive MVP of the 2008 Holiday Bowl. He started every game and finished the season with 83 tackles and five interceptions. Jairus announced that he would be entering the 2009 NFL Draft following his junior season.