Mr Guilherme Ribas > TozziniFreire Advogados > Sao Paulo, Brazil > Lawyer Profile

TozziniFreire Advogados
CEP 04038-904
Guilherme Ribas photo

Work Department

Competition Law




Guilherme has over 23 years of experience in competition law, having worked at both public agencies and private companies, assisting clients in different industries, such as pharmaceutical, telecommunications, internet, technology, payment service providers, food and beverages, textile, and plastics. His practice is focused on advising clients on cartel investigations and unilateral conducts, as well as on mergers and compliance programs. He served as general coordinator in the now extinct SDE (Secretariat of Economic Law) of the Ministry of Justice, where he conducted the first antitrust dawn raids and drafted the antitrust compliance guidelines (SDE Ordinance No. 14/2004).


  • Spanish
  • French
  • English


  • Director of Competition at IBRAC (Brazilian Institute of Studies of Competition, Consumer Affairs and International Trade), where he was director of Compliance & Investigations, Publications, Regulation, and president of the Advisory Board.
  • Member of the Competition Law Committee of OAB-SP (Brazilian Bar Association, São Paulo section) since 2008.
  • Founder of GEDECON (Study Group of Economic Law).
  • Member of CEDAU (Center of Studies on Administrative, Environmental and Urban Law).


  • Doctoral degree in Administrative Law from USP (Universidade de São Paulo), 2015.
  • Master’s degree in Commercial Law from USP, 2011.
  • University extension studies of Competition Law at FGV (Fundação Getulio Vargas), 2004.
  • Graduate of the Law School of USP, 1999.

Lawyer Rankings

Brazil > Competition and antitrust

TozziniFreire Advogadosremains one of the great references in Brazil when it comes to high-end corporate law firms‘. In competition and antitrust, the firm has established an impressive track record in the negotiation of leniency agreements with CADE, an area in which it maintains a large market share. The practice can also be seen representing companies in cartel and unilateral conduct investigations, and merger filings. Other distinguishing features include the team’s experience at CADE, with several of its lawyers having previously worked at the authority. Beyond the core competition group, the firm is also able to deploy cross-practice teams to cover the interconnected antitrust, compliance and white-collar criminal law aspects of complex cases. Tatiana Lins Cruz and Patricia Bandouk Carvalho are highlighted for their ability ‘to engage and dialogue with relevant authorities in this area at a high level‘. The well-regarded Marcelo Calliari leads the ‘highly qualified‘ team, which also includes Vivian Fraga, who is also a member of the firm’s Asia desk and as such acts for a number of Chinese, Korean and Japanese clients; Guilherme Ribas; and Marcel Medon Santos.