Thundering chants of "We are Hong Kong" from thousands of red-shirted fans reverberate through the city's stadium, tucked into the lush mountains and jagged skyscrapers of Hong Kong Island. Hong Kong's soccer team is playing against Lebanon, and the cheers die down for the opening stanza of the Lebanese national anthem.The polite applause for the opposing team takes a turn, though, when the national anthem of China – technically Hong Kong's anthem, too – begins.China's national anthem, "The March of the Volunteers," can barely be heard over loud booing from fans, some who turn their backs on the flag. Stadium personnel line the aisles, waving their hands to discourage fans, but it only makes them boo louder.The booing has become a regular part of international soccer matches in Hong Kong since 2014, when the city was embroiled in violent protests over China's refusal to allow residents to directly elect their leader. Soccer fan Rose Tse says it's a message to Beijing."I don't think this song is worth our respect," says Tse. "You need to earn our respect. You can't force people to respect you."When it comes to its national anthem, China begs to differ. Last month, China's legislature banned the use of the song in commercials and parodies, promising to punish those who do not "stand with respect and maintain a dignified bearing" when the anthem is played.Beijing later inserted this new law into Hong Kong's constitution, forcing Hong Kong's legislature to enact and enforce its own version of the law. This has left some Hong Kong lawmakers scratching their heads."How are you going to enforce it?" asks legislator Alvin Yeung Ngok-kiu, a lawyer by profession. "We're talking about a stadium, talking about hundreds of people. If all these people boo, are you going to arrest all of them? That is my concern. If a law is unenforceable, that law can hardly be respected."But Yeung says there's a bigger concern."Some Hong Kongers, they're not happy with Chinese rule," he says. "So they have their own way to express that. And I do have strong concerns that the national anthem law is another indication of Chinese encroachment to Hong Kong's high autonomy."Yeung says the new national anthem law will likely start to be enforced by next summer. Chung Kim-wah, who teaches social sciences at Hong Kong Polytechnic University, worries about what might happen at the first soccer match after the law goes into effect."I think when the government tries to enact the law, tries to implement the legal requirement, it should be very careful," warns Chung. "Otherwise, some confrontation or even violence is likely."Back at Hong Kong stadium, Rose Tse – who relishes booing China's national anthem – hasn't yet thought about what he's going to do after the new law goes into effect."Maybe I'll just stay home," he says. "Or I'll wait until the anthem's done before I enter the stadium. Or I'll just get up and go to the toilet as my own form of protest."Tse says he's not interested in going to prison, but he will if he has to. After all, that's what happened to Tian Han, the poet who wrote the lyrics to China's national anthemin 1935.Three decades later, Tian was caught up in Mao Zedong's Cultural Revolution, imprisoned in China as a "counter-revolutionary" and forced to drink his own urine. He died behind bars. But his lyrics, which call on all Chinese who refuse to be slaves to "rise up," are now protected with the threat of prison.-Yuhan Xu contributed research to this story. Copyright 2017 NPR. To see more, visit https://www.npr.org/.