When Adam Czerwoniec took to the streets of Warsaw to protest against a neo-Nazi rally last August, he steeled himself for the possibility of an ugly confrontation. But he didn't expect it would be with Polish police officers.

The 37-year-old social media specialist told VICE News his group was peacefully protesting against a rally by the National Radical Camp, Poland’s strongest ultranationalist movement, when a fellow protester refused to show her ID to police and was pushed against a wall. When Czerwoniec asked the officer to let her go, he got punched in the stomach.

“I didn’t give him any reason to do that,” he said. “I didn’t use any curse words and I wasn’t aggressive.” After the punch, Czerwoniec told the officer he was behaving “like a Gestapo,” and the officer threw him to the ground. Czerwoniec was then cuffed and taken to the police station, forced to strip naked and subjected to a full body-cavity search. Today, he faces a potential sentence of 1-3 years in prison for insulting a police officer.

Czerwoniec’s experience is part of an alarming trend of one-sided enforcement when it comes to political protests in Poland, according to a new Amnesty International report.

“Peaceful protest is a right, but in Poland it is under serious threat.”

The report tracks the increasingly heavy-handed approach that Poland’s populist government has taken toward peaceful protesters for liberal causes while regularly tolerating harassment or violence from far-right groups toward counterprotesters.

Amnesty warns that this one-sided policing taken alongside other trends — such as government-led harassment and surveillance — are threatening to snuff out the right to democratic protest, with dissenters frequently threatened with prosecution or subjected to violence. (The Polish government has yet to officially respond to Amnesty’s report, and it did not respond to VICE News’ requests for comment Monday.)

“Peaceful protest is a right, but in Poland it is under serious threat,” said Gauri van Gulik, Amnesty International’s Europe director.

“Polish authorities are threatening peaceful protestors with detention and prosecution, while in some cases police officers have even beaten and mistreated them. Many protestors are also put under surveillance,” Gauri van Gulik said.

The one-sided policing is another example of the ruling Law and Justice party’s accommodation of the country’s ultranationalist fringe, warn rights advocates. Since taking power in 2015, Law and Justice officials have legitimized and emboldened the country's far-right movements, simply by turning a blind eye to their activities. Now, those who challenge these groups are increasingly finding their efforts hampered, according to Amnesty researchers, as government officials often give preferential treatment to ultranationalist demonstrations over their opponents.

Czerwoniec said his experiences in August and at a subsequent counter-demonstration at the Independence Day rally in November suggested that police were applying different standards to the ultranationalists and those who protested against them. In August, he said, officers did nothing as marchers in the 30,000-strong nationalist rally threw beer bottles and hurled abuse in their direction.

Despite a court finding in January that the officer’s force against him was inappropriate, Czerwoniec is still facing a potential jail sentence over the August incident, and will learn of his fate at a hearing next month.

Czerwoniec worries that the government’s hardline stance is having a chilling effect and deterring people from taking to the streets. Still, he remains committed to protesting racism and xenophobia in his country.

“It’s not pleasant, but without this kind of sacrifice nothing will change,” he said.