You may be looking for Piotrków-Wiślica Statutes of 1346-1347.

The Piotrków Statutes were a set of laws enacted in the Kingdom of Poland in 1496. John I Olbracht of Poland made a number of concessions to the szlachta

Szlachta

The szlachta was a legally privileged noble class with origins in the Kingdom of Poland. It gained considerable institutional privileges during the 1333-1370 reign of Casimir the Great. In 1413, following a series of tentative personal unions between the Grand Duchy of Lithuania and the Kingdom of...

, whose support he required in war. Among other things, the szlachta were relieved of certain taxes and were granted exclusive rights to high Church offices. Restrictions were also imposed on the other estates.