This article proposes an analysis and commentary on the Law 1231 of 2008, “through which gets unified the invoice as securities for financing micro, small and medium entrepreneurs, among other regulations about it”, from a perspective that recognizes the economic role played by securities, the historical background to its inclusion in our legal system and its main issues in commercial practice. Also, study the process proposed by the legislator for the treatment of difficulties found during the effect and validity of the norms that ruled the securities in the Commercial Code.