Hundreds of lawyers in Hong Kong are scheduled to hold a silent march after China's most direct intervention in the Chinese territory's legal and political system since the 1997 handover.
Tuesday's protest march comes a day after China's parliament passed a ruling that effectively bars two elected Hong Kong pro-independence politicians from taking office.
The dispute flared after the young politicians deliberately misread their oaths of office in October, inserting expletives and draping themselves with "Hong Kong is not China" flags.
The National People's Congress in Beijing ruled on Monday that the two must swear allegiance to Hong Kong as part of China.
It also said that candidates would be disqualified if they changed the wording of their oath of office or if they failed to take it in a sincere and solemn manner.
The situation is seen among many across Hong Kong's legal and political elites as well as young citizens of Hong Kong as one of the biggest tests the global financial hub has faced since its handover to China, with some fearing its vaunted rule of law is under threat.
Leung Chun-ying, Hong Kong's chief executive, said he would implement China's ban on the two politicians.
"As chief executive, I have the responsibility to follow Hong Kong's Basic Law and implement the ban. Hong Kong is an inseparable part of China. Everyone in Hong Kong has a responsibility to respect the country's unity and safety," he said.
The prospect of the Chinese intervention prompted protests on Sunday in the former British colony, and it is now on high alert for any repeat of the weekend clashes.
Britain returned Hong Kong to Chinese control in 1997 under a "one country, two systems" formula that gives the territory wide-ranging autonomy, including judicial freedom guided by a mini-constitution called the Basic Law.
The protests on Sunday night were reminiscent of pro-democracy protests in late 2014 that paralysed parts of Hong Kong and posed one of the greatest political challenges to the central government in Beijing in decades.