Beijing has accused the former British colony's pro-democracy lawmakers of "malicious" filibustering to prevent some proposed bills from going to a final vote, effectively paralysing the legislature.
That backlog includes a bill that would criminalise abuse of China's national anthem.
The protests began over a now-withdrawn bill that would have allowed Hong Kong residents to be sent to the mainland for trial, and continued for more than seven months over police conduct and perceptions that Beijing is tightening its controls over the city's affairs.
Image copyright EPA Image caption Pro-democracy lawmaker Ted Hui tried to jump onto the chairman's bench What happened in the chamber?
It was the second time in 10 days that have legislators pushed and shoved each other over the procedures of electing a chairperson.
In a statement on Sunday, the United States' top diplomat said he had recently learned of Chinese government threats "to interfere with the work of American journalists in Hong Kong".
"Completely destroying Hong Kong".
Fighting broke out in Hong Kong's Legislative Council on Monday after a pro-Beijing lawmaker was elected to chair the committee that oversees the presentation of proposed laws.
Millions hit the streets a year ago for seven months of pro-democracy rallies that often spun out into clashes between police and petrol bomb wielding protesters.
Legislators in the Hong Kong assembly came to blows over this controversial bill.
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Police (R) take part in a clearence operation during a pro-democracy demonstration calling for the city's independence at a mall in Hong Kong on May 16, 2020.
If the State Department made a decision to decertify the territory, it still would ultimately fall to Trump whether to decide to end some, all, or none of the privileges Hong Kong now enjoys.
Under the "one country, two systems" arrangement, Hong Kong is promised a high degree of autonomy and democratic freedoms not available in mainland China.
China's leaders have dismissed popular anger in Hong Kong and instead portrayed last year's protests as a foreign-sponsored plot to destabilise the motherland.
They emerged from the West Kowloon magistrates court to applause, and led the crowds in chants together with "stand for Hong Kong, fight for freedom".
But Hong Kong is heading for elections to its own legislature in September and if last year's success for pro-democracy parties in district elections is repeated, government bills could be blocked. "A broad-brush interpretation of this law would signal the end of Hong Kong as we know it".
Article 23 of Hong Kong's mini-constitution, the Basic Law, says the city must enact national security laws to prohibit "treason, secession, sedition (and) subversion" against the Chinese government.
Signed into law in late November, it requires the State Department to certify annually whether Hong Kong is "sufficiently autonomous" to warrant the special USA trading privileges distinguishing it from mainland China. "Carrie Lam will have to live with her conscience", he said.
"If the national security legislation is not done during the annual session of the National People's Congress or shortly afterwards, is there any guarantee that it can be passed by the [Legislative Council] in the next two years?" the source wondered.
"China saying it wants to "improve" Hong Kong by stripping all its people's rights [and] liberties", he wrote in a tweet.