Tens of thousands of people have taken to the streets in Warsaw to protest against the Polish government.
The protesters say the governing conservatives run an undemocratic administration that violates European values.
A smaller protest against EU interference was also held.
The Law and Justice party has drawn criticism from the European Commission for its reforms of judicial, surveillance, and media laws.
The government passed legal amendments late last year which change the way the Constitutional Court operates.
The changes require a two-thirds majority of the 15 judges to support a ruling for it to be valid, and also stipulate a quorum of 13 judges for rulings to be valid.
Critics have said the changes mean the court is now unable to examine government legislation, and the issue has sparked mass protests in Poland.
The Council of Europe says changes undermine the rule of law, and the European Commission has launched an inquiry into changes to the Constitutional Court and media laws.
Recently approved media laws have placed public radio and TV under a new national media council and have given the treasury minister the right to hire and fire management.