Hong Kong(CNN) A year ago, Chinese-Australian dissident artist Badiucao was searching for a place in Hong Kong to display some of his political works, many of which are critical of the Chinese Communist Party.
Now he says he wouldn't even transfer through Hong Kong airport for fear of being arrested under the city's new national security law.
That's because the legislation, which came into effect late Tuesday, doesn't only clamp down on freedoms at home. It also puts foreign citizens who criticize the Chinese government anywhere in the world at risk of jail if they even set foot in the city -- even if they are just transiting through the airport.
"It's really concerning and terrifying, not just for residents in Hong Kong but anyone who cares about human rights in Hong Kong and human rights in China, in general," said Badiucao from his home in Melbourne, Australia.
For decades -- first under British colonial rule and then after its handover to China -- Hong Kong has offered legal protection from the mainland Communist Party. Chinese dissents, Western academics and global non-governmental organizations used Hong Kong as a safe space to meet, organize and criticize Beijing, mostly without consequence.
Whether it can continue to serve that function is now in doubt.
"There are crimes covered by this law which are purely about speech and so there is a chance that your speech outside of the country will then expose you to risk should you enter the jurisdictions," said Jeremy Daum, senior fellow at the Yale Law Paul Tsai Center.
"Hong Kong used to be a safe space. It's no longer a safe space."
On Wednesday, Hong Kong's top official, Chief Executive Carrie Lam, defended the new law, describing it as a "crucial step to ending chaos and violence that has occurred over the past few months" in the city.
The legislation was introduced by the central Chinese government in response to pro-democracy demonstrations that rocked Hong kong last year. Beijing saw the protests as a direct challenge to the ruling Communist Party, and blamed them on "foreign forces."
The law introduces four new crimes: secession, subversion, terrorist activities and collusion with a foreign country, which carry maximum sentences of life in prison.
Its primarily focus is on stopping local dissent. Yet section 38 has caught the eye of legal experts globally.
"This law shall apply to offenses under this law committed against the Hong Kong Special Administrative Region from outside the region by a person who is not a permanent resident of the region," is the unofficial translation of section 38 by state-run news agency Xinhua.
In short, even people who are not Chinese citizens and live outside of Hong Kong can fall foul of the new legislation.
Mainland China has a similar law, section 8 of the criminal code, but it can only apply if the crime is punishable in both China and the foreign country -- which means speaking out against the Communist Party likely would not be covered.
But section 38 of the Hong Kong national security law has no such exception. The act committed abroad only has to be considered a crime in Hong Kong.
The law isn't retroactive, which means that anything said or done before July 1, 2020, won't be taken into account. But for artists like Badiucao, who has no intention of stopping criticizing governments in his work, or displaying previous art that was political, the law could apply as soon as he sets foot inside Hong Kong -- even though he is now an Australian citizen.
Dissidents aren't the only people who are worried, either, as Western academics could be rethinking their travel to Hong Kong. Maggie Lewis, an expert in contemporary Chinese law at Seton Hall University, said she would now consider the risk differently every time she traveled the city.
"If you aren't thinking through what you did outside Hong Kong before you enter Hong Kong, I don't think you're going through the necessary thought process to be careful," she said.
Marco Rubio, a US Republican senator and frequent critic of China, went a step further on Wednesday, warning US citizens against traveling to the city. "Anyone American who now travels to #HongKong for business or pleasure is out of their minds," he posted on Twitter.
Hong Kong has long been home to events that could never be held in mainland China, including the annual commemoration of the 1989 Tiananmen Square massacre.
But even before the new legislation, critics of the Chinese government had found it difficult to make their voices heard in the city. In October 2018, a Financial Times journalist's working visa was controversially refused after he helped organize a talk with the leader of a pro-independence group.
One month later, dissident Chinese author Ma Jian had an event at a private space in Hong Kong abruptly canceled with no explanation. Badiucao's art show in the city was called off over "safety concerns."
Now, under the new security law, experts fear such moves could increase -- especially if staunch critics of the Communist Party feel they can't return.
Zhou Fengsuo, a survivor of the Tiananmen Square massacre and president of Humanitarian China, previously attended Hong Kong's June 4 memorial. He also took part in the Umbrella Revolution in 2014, when pro-democracy protesters took over the city's streets for months.
Now he feels it is likely no longer safe to return, despite being a US citizen -- and he's worried that in future, the Tiananmen Square memorial will no longer be viable.
Yale's Daum said section 38 of the law was designed, in particular, to target academics, NGOs and international dissidents who had previously used Hong Kong as a way into China.
"You can see throughout the law that the concern is that Hong Kong is being used as a beachhead to post a security risk to the mainland," he said.
Zhou agreed: "I believe most dissidents and artists, academics will be reluctant to go to Hong Kong, our of justifiable fear from the national security law."
Many law experts and dissidents agree it remains unclear how worried critics traveling through Hong Kong should be, or exactly how the Chinese government intends to use the law.
As with much of Beijing's national security legislation, the Hong Kong law is written broadly enough that it can be used as required by the Communist Party leadership.
Seton Hall's Lewis said the Chinese government might quickly use it to arrest a few big names, scaring smaller players into submission, or quietly keep it in reserve.
"It is another arrow in Beijing's quiver to arrest people that Beijing has determined as breaking the law and that law is construed broadly," Lewis said.
Badiucao said the vague wording of the law was a deliberate move by the Chinese government.
"When you don't know where the red line is ... they can expand their power as they wish," he said.