Bishops of the Polish–Lithuanian Commonwealth were one of the highest ranking officials who could sit in the Senate of Poland.
Only Roman Catholic bishops sat in the Senate (see Senatorial offices for details).
In addition, the Archbishop of Gniezno had the power to call a new Senate session, if he deemed it important to do so, even in the absence of the King.
He could also invoke the "de non praestanda obedientia" article, giving the country the right to legally depose the King.
That person acted as the Archbishop's messenger during Senate meetings, giving signs (by moving a cross) that conveyed how the Archbishop wished his allies to vote.