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Mateusz Kosowicz


Mateusz specializes in commercial disputes, white-collar crime and investigations.

Since 2018, Mateusz has been advising clients in multinational and complex commercial disputes and criminal proceedings. He has represented clients from various sectors before common, administrative and arbitration courts – as well as before law enforcement agencies and regulatory authorities. He has also assisted in a number of internal corporate investigations. 
Before joining the firm, he worked in the litigation departments of renowned international and Polish law firms.  


Representative matters

A foreign airline in numerous (EUR10m) administrative proceedings for the imposition of fines in connection with the transmission of PNR data.  An international company from the telecommunications industry in a criminal case concerning the disruption of a public tender.  An international company from the agricultural sector in a complex criminal case involving fraud and acting to the detriment of a creditor. An international company from the alcohol industry in criminal proceedings regarding the promotion of alcohol on social networking sites.  A foreign bank in a EUR12m case against the shareholders of a bank's debtor for compensation for preventing the enforcement of the claims. An international insurer in EUR1m disputes arising from an aircraft accident. An international company from the waste management sector in a complex internal investigation and a case of infringement of personal rights, as well as in a dispute over remuneration under a public-private partnership agreement. A foreign airline in civil disputes in the area of aviation law.    A Polish bank in EUR1m real estate disputes.   A Polish investment fund in a EUR10m dispute over the restructuring of a company's debt;  an international bank in a criminal case for the seizure of funds on suspicion of money laundering.

Pro bono

Advised at the Student Legal Clinic at the University of Warsaw

Leadership Positions And Professional Affiliations

  • Member, Warsaw Bar



MA, Law, University of Warsaw, 2020 Student exchange, Georg August University of Göttingen, 2019-2020


A&O Shearman was formed on May 1, 2024 by the combination of Shearman & Sterling LLP and Allen & Overy LLP and their respective affiliates (the legacy firms). Any matters referred to above may include matters undertaken by one or more of the legacy firms rather than A&O Shearman.