Several thousand people have rallied in Warsaw to protest against controversial new court reforms they see as a threat to judicial independence.
The changes require the Polish parliament to submit judges for nomination which is the same process as in the United States.
"Shame, shame" chanted protesters gathered in Warsaw under Polish and European Union flags, and calling Jaroslaw Kaczynski, the chairman of PiS and the country's de facto leader, a "dictator".
There have been a strong of protests across the country during nearly the entire reign of the Law and Justice Party as many see the democratic process under siege.
The law passed last week gives lawmakers a dominant role in appointing judges, a move that opposition parties and rights groups said would make jurists subject to political influence. The other legislation mandates that the current judges in the country's Supreme Court be dismissed-except those approved by the minister of justice.
An overhaul of the constitutional court and increased control over the prosecutor-general's office by the Justice Ministry have raised eyebrows overseas.More news: Bihar crisis: Nitish, Lalu call separate meetings with lawmakers
Poland's senate on Saturday adopted two controversial judicial bills, which the opposition claims is yet another step by the conservative majority towards undermining the separation of powers.
"Today we know that a great fight has begun and we know we must be together, we know we must fight against them together", said Grzegorz Schetyna, leader of the opposition Civic Platform party.
Poland's TVP television, controlled by the state, said the protests and calls to block Tuesday's debate were "an attempt to organise a coup against a democratically elected power".
Protesters in front of parliament.
Police estimated the crowd at about 4,500, a number far lower than city hall estimates, which put the number above 10,000. At night, thousands more gathered at Krasinski Square, the site of Trump's speech, and the location of the Supreme Court.
Smaller protests took place also on Sunday in Krakow, Katowice and other Polish cities.