Judges from 20 European countries joined their Polish counterparts on a silent march of protest through Warsaw on Saturday, in an unprecedented public display of international judicial solidarity.

Wearing their robes, the judges, along with thousands of demonstrators from across the country, were marching against repressive new measures aimed at Polish judges that the president of the supreme court warned could lead to Poland’s eventual departure from the EU.

The protest made its way from the Polish supreme court through central Warsaw to the parliament building. Countries represented included the Netherlands, Norway and Bulgaria.

Demonstrators shouted “Bravo!” and “Thank you!” as the European judges walked past in silence. “It is an extraordinary event,” said Andrea Chis, an appellate court judge from Romania. “This is the first time we have come together to defend the independence of the judiciary, not just in Poland but across the EU.”

Hundreds of Romanian judges and prosecutors have signed a letter of “unconditional support” for their Polish colleagues. “The support is extremely important to us, we treasure it,” said Monika Frąckowiak, a district court judge from the north-west city of Poznań, and a co-organiser of the event. “We are European judges, we are part of Europe, and this is confirmation of that.”

Polish judges involved in politically sensitive cases, or who have expressed opposition to challenges to judicial independence, are frequently threatened with disciplinary proceedings and even criminal charges, and in many cases, subjected to state-led campaigns of intimidation. After taking office in 2015, Poland’s ruling right-wing Law and Justice party assumed direct control of the National Council of the Judiciary (KRS), a formerly independent body that oversees the appointment, promotion and discipline of all Polish judges. This allowed the government to fill a newly created judicial disciplinary chamber with party loyalists who have since proceeded to launch disciplinary proceedings against any judge who questions the new regime.

Facebook Twitter Pinterest Lawyers from Portugal show solidarity with their Polish counterparts. Photograph: Czarek Sokołowski/AP

In December, the Polish supreme court, which is still independent, ruled that the KRS and the new disciplinary chamber were unlawfully constituted. The government responded with legislation making it illegal for any Polish judge to question the legality of its appointments – in effect, to ban Polish judges from complying with a ruling issued by their own supreme court.

If enacted, the proposals, which are currently under consideration in the Polish senate, would also make it illegal for Polish judges to refer legal questions directly to the European Court of Justice – despite such referrals being central to the functioning of the European legal system.

That led to a stark warning last month from Małgorzata Gersdorf, president of the Polish supreme court, that “such a solution will lead directly to Poland’s exit from the EU”.

Her message appeared to be echoed by Koen Lenaerts, the president of the ECJ, during a visit to Poland on Thursday. “You can’t be a member of the European Union if you don’t have independent, impartial courts operating in accordance with fair trial rule, upholding union law,” he told an audience at the University of Warsaw.

Saturday’s public display of support from their European colleagues is the culmination of several years of soul-searching on behalf of members of a profession that has found itself dragged unwillingly into the political fray by increasingly overt attacks on judicial independence in several European countries.

Representatives of European judicial associations say that the traditional refrain that judges should only “speak through their judgments” has been found wanting.

“Judges are reaching out to citizens, saying ‘defend us, so that we can defend you’,” said Kees Sterk, a Dutch judge and president of the European Network of Councils for the Judiciary.

“In countries where judicial independence is respected, then of course judges should not get involved in politics. But when judicial independence is being destroyed, you cannot expect them to allow themselves to be led like lambs to the slaughter. It is not just that judges are allowed to fight – it is their duty.”