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

TozziniFreire Advogados
CEP 04038-904
Guilherme Ribas photo

Work Department

Competition Law




Guilherme has twenty years of experience in competition law, having worked at both public agencies and private companies, assisting clients in different industries, such as pharmaceutical, telecommunications, 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 publications at IBRAC (Brazilian Institute of Studies of Competition, Consumer Affairs and International Trade) (2016-2019), where he was director of Regulation, counselor and president of the Advisory Board.
  • Member of the Competition and Economic Regulation Studies 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 Advogados ‘has a multi-disciplinary profile and unique knowledge of the antitrust authorities’. The department continues to see organic growth; with Patricia Bandouk Carvalho‘s election to the partnership being followed by that of Mario Pati in February 2020, adding further depth to an already sizeable team. The group is equipped to handle the gamut of competition matters and – outside of the practice itself – benefits from the firm’s strong compliance and corporate and M&A departments. Of particular note is the firm’s impressive track record in negotiating leniency and settlement agreements, where it has a large market share. Marcelo Calliari heads the department, which includes key partners Tatiana Lins CruzGuilherme Ribas and Vivian Fraga.