This work makes a comparative analysis of the judgment of lawsuits that questioned the validity of laws that guarantee the impunity of the sectors involved with the political repression during the National Security dictatorships. For the comparison, two cases were selected for analysis: the “Simon Case”, judged in June 2005 by the Argentine Supreme Court of Justice, and the ADPF 153, judged in April 2010 by the Brazilian Federal Supreme Court. The decisions are compared and, after, we try to identificate what explains them, verifying their connection with the politics of memory that have been implemented in each context.