Siena holds a Bachelor of Laws/Bachelor of Civil Laws from McGill University and a Bachelor of Arts in Journalism and Anthropology from Concordia University. She is a former legal intern in the Appeals Division of the Office of the Prosecutor at the ICTY and summer litigation associate with Morrison & Foerster in New York. She has worked in human rights law, international development, and freelance journalism in Cambodia, Kenya, Uganda, Syria and Kosovo. In August 2014, Siena will begin a clerkship at the Court of Appeal for Ontario. In 2015, she will clerk for Justice Cromwell at the Supreme Court of Canada.