"People who would otherwise be happy to join in and take part are now thinking twice," says Jason Ng, a member of the Progressive Lawyers Group, a pressure group.

"(They're thinking) it's really not worth putting my career at risk when the potential benefit is close to nothing."

Kong Tsung-gan, author of "Umbrella: A Political Tale from Hong Kong," Kong has tracked almost 40 civil and criminal cases against pro-democracy figures, some of which have already resulted in imprisonment, fines, and disqualification from the city's parliament.

He told CNN the scale and scope of the prosecutions, particularly the tough sentences for those convicted, are "unprecedented."

In the past, he said, "it has been the case that one activist here and another there would be prosecuted, and perhaps convicted of unlawful assembly and the like, but the person would normally receive a fine or a prison sentence not greater than three weeks."

Antony Dapiran, a Hong Kong lawyer and author of "City of Protest," said the "incessant slow drip of legal action over the course of this year has been... effective in keeping pressure on activists who do not know what and when the next government action will be, and (that is) therefore having a stifling effect on their activities."

A spokesman for Hong Kong's Department of Justice said "allegations of political prosecution or persecution are entirely unfounded," adding the DOJ is "committed to safeguarding the rule of law and judicial independence in Hong Kong, as well as keeping criminal prosecutions free from any interference."

Chilling effect

The sheer number of cases has seen the city's pro-democracy movement enter a repetitive and energy-sapping cycle of court hearings, protests against the prosecutions, and vigils outside prison or judicial buildings.

Around 1,800 people joined a march led by Wong Sunday, which he had billed as perhaps his last part to protest with his supporters before he returned to jail.

"I'm satisfied that a group of Hong Kongers walked with me in my last rally today although not a lot of people came out," he said.

"It doesn't really matter to us how many people came out as long as we did our best and provided an opportunity for our supporters to show solidarity," pro-democracy icon "Long hair" Leung Kwok-hung -- who was also disqualified from office earlier this year -- told the paper.

Dapiran said the prosecutions were designed "to make the cost of dissent intolerably high, and to make in particular Hong Kong's politically active youth think twice about whether they are willing to pay an increasingly steep price -- jail, bankruptcy, the effect all of that might have on future careers -- to express their political views."

The 2014 protests were largely driven by high school and university students, who took to the city's streets in huge numbers and camped out for weeks on end. A small number of them went on to become lawmakers in 2016 elections. Of the cases Kong tracks, more than 60% of those facing prosecution are under 30.

"They want to say, If you confront us, we will destroy your life," Kong said.

Hong Kong's DOJ rejected the suggestion that it was prosecuting an unprecedented number of cases.

"The Occupy Movement is an unprecedented situation which involves a large number of participants," a spokesman said, referring to the 2014 protests. "The DOJ does not intentionally prosecute more people than it should do so."

Criminalizing speech

In particular, China's government has taken a harsh line on advocacy of Hong Kong independence, with President Xi Jinping warning in a visit to the city earlier this year such talk was a "red line" for Beijing.

In October, China introduced a new National Anthem Law, which punishes those who "disrespect" the song with up to 15 years in jail. That move comes after Hong Kong football fans repeatedly booed and jeered the "March of the Volunteers" as it played before their international matches.

While the Chinese law currently does not apply to Hong Kong, it is being adopted into the city's statutes, and an amendment to the original law which would extend the punishment to a maximum of three years is being considered by Beijing.

Worse to come?

Article 23 of Hong Kong's constitution, Basic Law, calls on the city's government to "enact laws on its own to prohibit any act of treason, secession, sedition, subversion against the Central People's Government," but so far, repeated administrations have dragged their feet on doing so.

"Trust in the Hong Kong government, not even to mention the (Communist) Party, is so low that any introduction of Article 23 legislation will be viewed as an attack on civil liberties," Kong said.

"In theory, Article 23 legislation could be used to effectively outlaw a broad spectrum of the pro-democracy movement."