This paper aims to analyse one electoral reform in particular: the establishment of electoral thresholds, introduced into the Colombian electoral system in 2003 and reaffirmed in 2009. The threshold is a regulatory provision that prevents access by political parties, political movements and groups of citizens who have not achieved a certain number of votes, i.e. the number of votes required by law, which means that if they do not obtain it, they are not entitled to participate in the distribution of seats, according to the electoral formula in force, in the corporation to which they aspire. It is also known electorally as an electoral barrier, legal barrier, minimum barrier or minimum threshold.