Partner and one of the founders of Pietrzak Sidor & Wspólnicy Law Office. Graduate of the Faculty of Law and Administration at the University of Warsaw. He holds a Cambridge University Certificate in English and European Law. Member of the Warsaw Bar Association, and since November 2016 Dean of the District Bar Council in Warsaw. From 2010 to 2016, he was chairman of the Human Rights Committee of the Supreme Bar Council. In 2016, he was appointed by the UN Secretary-General to the five-member Board of Directors of the United Nations Fund for the Relief of Victims of Torture and in 2018 and 2019 he was Chairman of the Board. Recipient of numerous awards given for legal work in support of civil society and human rights, including the Edward Wende Award and the CCBE Human Rights Award. Awarded the "Advocacy of Merit" badge.

He primarily handles criminal law cases, with a particular focus on business criminal cases and compliance. He also specializes in human rights and constitutional law.

He has been recognized three times in the Rzeczpospolita ranking as the best lawyer in the category of criminal law for business. Ranked in the European ranking of Chambers Europe in the category of best Polish lawyers in business criminal law.

He is a member of international legal organizations such as the European Criminal Bar Association, the National Association of Criminal Defense Lawyers in the United States and The Legal Experts Advisory Panel created under Fair Trials International. Until 2014, he was a member of Perren Buildings Chambers, based in London. In 2014, he became a member of Doughty Street Chambers, based in London. He was a permanent representative of the Polish Bar at the Council of Bars and Law Societies of Europe (CCBE) in the Commissions: Human Rights and Permanent Delegation to the Strasbourg Court. He is a member of the Bar Association at the International Criminal Court and was listed as a lawyer at the Special Tribunal for Lebanon.

He is one of the founders of the Prof. Zbigniew Holda Association. He was the coordinator of the program "Human Rights and Settlements with the Past," conducted by the Helsinki Foundation for Human Rights. He was a member of the Social Council of the Human Rights Ombudsman and a member of the Program Council of Amnesty International Poland.