The primary goal of this study is determination of the authorship of the article entitled »Croats on the Second Vatican Council«, which was published in magazine Hrvatska revija [Croatian revue] in 1963. The article was signed by pseudonym Vigilantibus iura, and in the existing literature researchers have proposed several possible authors. Namely, the most common suggestions were Krunoslav Draganović and Ivan Tomas, and some of the researchers assumed that beside them one could include Krešimir Zorić, too. However, present-day state of research revealed that both assumptions were wrong, or at least inadequate.This article published in 1963 drew a great attention of audience, especially in the emigration circles. Soon after, Hrvatska revija started to publish a vivid discussion based on the statements published in the article. Some of the critics were Mirko Živković, Josip and Stjepan Torbar, and Jozo Kljaković. Unknown Vigilantibus iura has replied to these criticisms, and this debate was finished in 1964, with a special editorial report about it. Yet, it seems that Jozo Kljaković was eager to continue this polemic, but the chief editor of Hrvatska revija, Vinko Nikolić, did not want to prolong it. Therefore, Kljaković has decided to stop his cooperation with Nikolić and Hrvatska revija. On the other hand, this polemic had its reflection on some other emigrants’ publications and private correspondence. Thus, author of this study delivers a brief sketch of contemporary political context, with a stress on the diplomatic relations between the Holy See and Socialist Federative Republic of Yugoslavia; especially regarding the position and role of the Croatian political emigration, since this was crucial factor in the process of these negotiations. This study is based on the information derived from various relevant archival sources, among which Legacy of Vinko Nikolić – presently kept in the National and university library in Zagreb – certainly stands out. A right combination of methods, relying on the written sources and oral history, finally has revealed that Ivan Tomas was the author of the articles published by the pseudonym Vigilantibus iura.