After Law School he clerked for the Argentine Supreme Court. He then started his career in law teaching at Universidad Austral in 1995. Legarre moved to UCA in 2007. Since 2012 he is also a visiting professor at the University of Notre Dame Law School (Indiana) and at Strathmore Law School (Kenya), where he developed a teaching system of expressing knowledge through art.
Legarre's academic interests include constitutional law and jurisprudence. He also teaches a workshop on creative writing for law students. Together with a group of students he founded in 2006 the online magazine Sed Contra and was the first editor-in-chief. The magazine is now in its 22nd issue and has published articles by more than 100 law students.
Legarre is an independent researcher at CONICET, the Argentine National Council for Research. He is also a freelance writer for La Nación, a leading Argentine newspaper.