After three years of sustained legal efforts by Sin Fronteras, Mexico’s Federal Court for Fiscal and Administrative Justice validated the proof of duration of residency and the right to qualify for naturalization of a national from Guatemala who has resided in Mexico for 19 years. Previously, the resident’s duration of residency and, therefore, ability to qualify for naturalization was in doubt. Once published, the decision has the potential to create a legal precedent for further naturalization cases based on Mexico´s 2009 Nationality Law. Sin Fronteras, a MacArthur grantee, is one of Mexico’s leading migrant advocacy organizations and works on behalf of refugees, asylum seekers, and migrants in the Americas.