Precision Refined Through Decades of Experience
and Guided by Passion for Tax Related Matters.

Cross-Border Tax Expertise.

Two tax experts with different experience but similar mindsets joined forces to address complex cross-border tax problems for private and public stakeholders.
We act individually or together as tax experts, expert witnesses, special counsel and policy advisors — at the intersection of international tax law, investment arbitration, and global policy.

Explore Our Expertise Meet the Founders

USD 120 billion + Combined value of disputed tax risk in cases in which we were engaged

300+ Combined scholarly publications & books

55+ Combined years at the international tax frontier

40+ Combined courts and investment treaty tribunals citing our analysis

Expert Advice on International Tax Related Matters.

We act as tax experts and strategic policy advisors for businesses in complex international tax-related matters. Clients with roles as global or regional tax directors, general counsel, and CFOs/CEOs, as well as governments and international organizations seeking guidance on the intersection of taxation and investment treaty protection, may benefit most from our expertise.

Investment Arbitration & Tax Litigation.

As governments have become more proactive and sophisticated in designing and enforcing their tax laws, tax and tax-related investment disputes have become more prevalent. Where arbitration or litigation teams in law firms and tribunals need international tax counsel, we act as special counsel and as expert witnesses.

Strategic Policy & Thought Leadership.

Equipped with deep focus on complex tax problems and rich international experience, we bring a solid perspective on global tax policy development. We advise governments, international organizations, and private stakeholders navigating the evolving landscape of cross-border taxation.

Błażej Kuźniacki, Ph.D., Hab.

Professor of law · attorney at law · award-winning author

Błażej Kuźniacki is Professor of Law at Lazarski University, External Senior Research Affiliate at the Singapore Management University, Michigan International and Comparative Law Research Scholar at the University of Michigan Law School — Fulbright Senior Research Awardee (2026–2027). He is an award-winning author of 150+ scientific publications, some of which are cited by supreme courts in several jurisdictions, the OECD, the WBG and the CIAT. Błażej specializes in the intersection of taxation matters with international investment, trade and public international law as well as AI-driven tax systems.

Full biography

Prof. dr. Stef van Weeghel

Professor of International Tax Law at University of Amsterdam

Stef van Weeghel is Professor of International Tax Law at the University of Amsterdam and ex-Global Tax Policy Leader at PwC, ex-Chairman of the IBFD Board of Trustees, ex chair of IFAss Permanent Scientific Committee. Longtime consistently ranked Band 1 by Chambers & Partners, he acts as counsel and expert witness in international tax litigation and investment treaty arbitration.

Full biography

Our Founders