Pan-democrats in Legco have accused the authorities of using a colonial-era sedition law to arrest a district council chairwoman as a way of getting political revenge, while a human rights group warned the move shows freedom of expression in Hong Kong has deteriorated even further.
Police say the Democratic Party's Cheng Lai-king, who chairs Central and Western District Council, is suspected of inciting violence and hatred, over a post on social media containing personal information on a police officer suspected of shooting an Indonesian journalist in the eye during a protest.
A Facebook post that has since been deleted called for an "eye for an eye" and urged the policeman in question to "turn himself in". Cheng was released on bail on Thursday afternoon, following her arrest on Wednesday night.
The pro-democracy camp said the "seditious intention" law was last used in the 1960s by the colonial government to silence political dissent.
Democratic Party lawmaker James To said the SAR government is using the case against Cheng to test how far it can go with existing anti-sedition laws.
The Civic Party's Dennis Kwok, meanwhile, said the case will also give people a glimpse of what Article 23 national security laws would bring.
"Unfortunately, the government of today decided that it would use these colonial laws to silence political discontent, clearly in political revenge for what the district councillors have been so bravely and courageously doing: their duty," Kwok said.
"This government has shown that it is capable of using these laws and if there's Article 23 legislation, then they will use it, not for the purposes of so-called 'national security', but for silencing and prosecuting political dissent."
Hong Kong Human Rights Monitor also criticised Cheng's arrest, accusing the police of becoming "an organisation that suppresses expression".
In a statement, the group said the arrest shows that freedom of expression in Hong Kong has deteriorated even further, adding that the offence of "seditious intention" is too broad and contravenes the Basic Law, the Hong Kong Bill of Rights, and the International Covenant on Civil and Political Rights.
However, DAB lawmaker Holden Chow said the police were only acting in accordance with the law, and the opposition camp is just looking for excuses to complain about the force's actions.
Chow added that Cheng's social media post could also be classed as misconduct on her part.
The legislator's party-mate, Leung Che-cheung, added that there are limits when it comes to freedom of speech and politicians aren't exempt from the consequences of breaching the law.