Unparalleled Experience and Proven Expertise

Unique Combination of Skills

Antuña & Partners founder, Antolín Fernández Antuña, has intervened in more than 40 investment arbitration cases and performed 42 cross-examinations as counsel over the last five years, which goes to show he is one of the most experienced lawyers in investment arbitration in the world today.

Additionally, he has proven expertise in quantum matters: while acting as counsel for the State in Investor-State arbitration, he has coordinated expert teams and examined some of the world’s best quantum experts in more than 25 cross-examinations. Before defending the State, he worked for ten years as State Finance Inspector and international taxation expert, having audited a wide range of multinationals with up to $50 billion in revenue.

Instructing Experts

In international arbitration, where gains and losses can be significant, having the best experts on your side is a must. However, to be effective, these experts have to be properly instructed.

Antuña has successfully instructed quantum, regulatory, and technical experts in more than 40 Investor-State arbitrations.


Cross-examination is a typical element of common-law jurisdictions. In international arbitration, it is probably the core of every hearing, and many times the deciding factor when resolving a dispute.

That is why cross-examinations are reserved for the most experienced lawyers of each party.

Antuña has fifteen years of experience in examining experts. Moreover, in Investor-State arbitration, in the last five years alone, he set a world record of 42 cross-examinations (28 quantum experts, seven regulatory experts and seven witnesses).


In international arbitration, stakes are high, and counting with the best of the best in every field and with complementary teams is a priority. That is why co-counseling between several top law firms for each side is commonplace.

Antuña has vast experience in co-counseling with several top law firms.