Police said 14,000 took part at one point, while Warsaw City Hall put the figure at 50,000. Some of the demonstrators then moved on to protest outside parliament.
Polish Interior Minister Mariusz Błaszczak said that a lot of the people were passers-by who happened to be there "because it is summer ... many were strolling", while others were spectators.
Police stopped 270 people, asking them for their ID, fined 52 people and detained one, a spokesman said, adding that 200 people will face misdemeanour charges.
One group of people blocked a police car during protests, another blocked a street and were forcibly moved by police at 3:30 on Friday morning, the police spokesman said.
A number of prominent opposition politicians joined in the protests, with Grzegorz Schetyna, the leader of Poland’s main opposition party, the Civic Platform, accusing the government of wanting “a return to communism”.
Poland's ruling conservatives have said sweeping changes are needed to reform an inefficient and sometimes corrupt judicial system.
But Ryszard Petru, the leader of the opposition Modern party, said on Thursday that it was a “bad day for Polish democracy,” adding that the ruling conservative party “bulldozed over Polish democracy” by passing a bill to “eliminate the Supreme Court”.
On Friday, the Polish Senate is to consider a government-backed Supreme Court reform bill, passed in the lower house on Thursday, which, if it becomes law, will force all of the court’s current judges into retirement and give the president powers to choose who to reinstate.
PiS supporters have criticised Polish courts for taking too long to hear cases, and have accused judges of being an elite, self-serving clique often out of touch with the problems of ordinary citizens.
Protests outside the Presidential Palace. Photo: PAP/Bartłomiej Zborowski.
But opposition MPs and the thousands of people who have taken part in nearly a week of protests outside Poland’s parliament have called the planned changes a “coup” and an attack on democracy, accusing the governing Law and Justice (PiS) party of aiming to stack courts with its own candidates and to dismantle the rule of law. (vb/pk)
Source: PAP