Marek is a Member of the European Court of Auditors (2021 – 2023 Member of the Chamber V on Financing and administering the Union, since 2023 Member of the Chamber III on External action, security and justice). In the past Marek was Vice-President of the Polish Supreme Audit Office (2019 – 2021), Member of Parliament – Deputy of the Sejm of the Republic of Poland (2005 – 2019) and Expert at the Presidential and Executive Office, Law and Justice Party HQ (2002 – 2005).