HONG KONG — If his cutoff T-shirts, close-cropped hair and long, thin beard were not enough to make Koo Sze-yiu stand out among the masses who took to the streets to protest in Hong Kong, there were also the coffins.
Mr. Koo often built the wooden coffins by hand, adorning them with messages denouncing China’s Communist Party. For decades, Mr. Koo, 75, carried the coffins as props in protests in Hong Kong, and he had planned to do the same to mark the Beijing Winter Olympics in February. But before he could, he was arrested by the Hong Kong police.
On Tuesday, Mr. Koo was convicted of attempted sedition and sentenced to nine months in prison, underscoring the authorities’ drive to stamp out even peaceful, small-scale displays of dissent that were once common in Hong Kong. Mr. Koo’s case has drawn particular concern because he has been diagnosed with Stage 4 colon cancer, leading friends to fear he could die in prison even while serving a relatively short sentence.
But Mr. Koo urged the court not to show mercy on him.
“I don’t mind being a martyr for democracy and human rights,” Mr. Koo said before his sentencing. “In mainland China there are many political prisoners, prisoners of conscience and political dissidents.”
“Compared with human right lawyers in China, what I have sacrificed is nothing,” he added, referring to activist lawyers in the mainland who have been imprisoned, tortured or held indefinitely under house arrest.
Since 2020, the Beijing-backed authorities in Hong Kong have carried out a sweeping crackdown to muzzle dissent after months of antigovernment protests that roiled the semiautonomous Chinese city. The campaign has targeted prominent opposition figures and former lawmakers, as well as some of the most influential lawyers and publishers. It has also ensnared grass-roots activists like Mr. Koo.
Pro-democracy demonstrations in Hong Kong had for years attracted hundreds of thousands of people. Mr. Koo’s planned protest in February, which he had told the local news media about, would have been a small affair in comparison. He had wanted to walk alone to Beijing’s representative office in Hong Kong, pushing a coffin on a trolley, bearing the slogan, “Down with the Communist Party, End One Party Dictatorship” and a profane message about the national security law.
His lawyers had argued that because his protest plans involved no acts of violence, they should not be considered a crime. Mr. Koo had even intended to march from a nearby police station to make it easier for officers to monitor the protest, they said. But prosecutors argued that such a protest amounted to an action plan to inspire Hong Kong residents to use illegal means to overthrow the government.
Mr. Koo’s supporters and human rights activists say his case shows how greatly speech rights have been curtailed in Hong Kong.
“There are now ideas you cannot touch without losing your freedom,” said Avery Ng, secretary general of the League of Social Democrats, a leftist, pro-democracy group in Hong Kong. “It’s so heartless. If they will send this guy with fourth-stage cancer to jail, what about the rest of us? But that’s the new reality those of us in Hong Kong have to accept.”
Principal Magistrate Peter Law, who heard Mr. Koo’s case, said he had already been diagnosed with cancer when he committed the crime, so that would not be factored into his sentencing.
Mr. Koo was not always a government critic. As a young man growing up in Macau, a Portuguese colony that returned to Chinese control in 1999, he was active in a Communist Party-linked labor union and liked to listen to patriotic “red songs,” said Tsang Kin-shing, a friend and fellow activist. But after China’s Communist Party sent troops to crush pro-democracy demonstrations around Tiananmen Square in 1989, Mr. Koo turned against Beijing.
Like many opposition activists in his generation, the Tiananmen crackdown shaped Mr. Koo’s political views. He and others saw the struggle for democracy in Hong Kong as closely bound with such efforts in mainland China. They held annual vigils for those killed in 1989, which were attended by tens of thousands at their peak in Hong Kong’s Victoria Park until they were effectively banned in recent years.
In 2012, he was one of a group of activists who landed on uninhabited islets in the East China Sea claimed by both Tokyo and Beijing. They were detained by the Japanese Coast Guard and sent back to Hong Kong, where they arrived to a heroes’ welcome. The group’s members said the protest was meant to show that the Communist Party did not have a monopoly on patriotism in China.
For a time, the views of Mr. Koo’s generation of activists were discounted by younger Hong Kong activists who have expressed little interest in the political fate of the rest of the country, or who have even called for Hong Kong’s independence from China. But such differences have faded since Beijing accelerated its crackdown on the territory, fueling broader solidarity across the opposition movement.
Mr. Koo was not prosecuted under the national security law, but rather a colonial-era sedition law. Before the current crackdown, the sedition law had last been used in the 1960s. The maximum potential sentences are shorter: two years in prison, as opposed to life imprisonment under the security law. But the sedition law enables the authorities to target smaller protests criticizing the authorities that don’t involve other alleged criminal acts, which is often a component of security law prosecutions.
Going after such small-scale speech crimes will continue to damage the reputation of the government, and undermine the efforts of its new leader, John Lee, to promote Hong Kong as an open, international city, said Thomas E. Kellogg, executive director of the Center for Asian Law at Georgetown University.
“The Lee administration will find it hard to convince anyone in the international community that it is serious about maintaining Hong Kong’s vaunted rule of law when as it continues to prosecute activists like Koo and so many others,” Mr. Kellogg said.
Joy Dong contributed reporting.