“IF YOU don’t deal with the two cancer cells, you will harm the entire body.” So said a Chinese official, Zhang Xiaoming, when justifying his government’s decision to block two lawmakers who support Hong Kong’s independence from China from taking up their posts in the territory’s Legislative Council, or Legco. The move has angered many people in the territory. Hours before it was announced by the national legislature in Beijing, thousands of protesters in Hong Kong took to the streets; some of them scuffled with riot police. Not everyone sees separatism as a cancer.

The intervention by the National People’s Congress (NPC), as China’s parliament is known, is the first of its kind since Britain handed Hong Kong back to China in 1997. The NPC has ruled before on constitutional matters in Hong Kong, but never before has it done so while judicial proceedings are under way in the territory on the same issue. On November 3rd a court in Hong Kong began hearing a case filed by the local government aimed at barring the two, Sixtus Leung and Yau Wai-ching, from Legco. Rather than wait for a verdict, China has decided to step in right away. Leaders in Beijing were enraged when the two referred to China in a derogatory way and displayed a banner saying “Hong Kong is not China” while they were being sworn in on October 12th. Mr Zhang, who is China’s most senior representative in Hong Kong, told lawmakers in Beijing that in “fighting and containing the spread of separatist forces in Hong Kong” the central government’s position was “clear and firm”. The NPC’s ruling says that oaths must be taken “accurately, completely and solemnly” in order to be valid.

Hong Kong’s government has expressed support. The chief executive, Leung Chun-ying, went further. He told reporters that the rise of pro-independence activism could require the enactment of new legislation on internal security. Hong Kong’s post-colonial constitution, known as the Basic Law, says the government should pass such a bill. But an earlier attempt to do so triggered huge protests in 2003 that prompted the authorities to shelve their plans. There could be more unrest if the government tries again. In anticipation of the NPC’s ruling, thousands of people demonstrated outside the central government’s liaison office in Hong Kong. Some shouted “Hong Kong independence!”. Police used pepper spray to try to disperse them. Demonstrators unfurled umbrellas to defend themselves, mimicking their use in 2014 during the “Umbrella Movement” when pro-democracy protesters paralysed busy commercial districts with weeks of sit-ins. It was that movement, and China’s refusal to grant its participants’ demands for full democracy in the territory, that led to the birth of independence-leaning groups such as Youngspiration, to which the two separatist lawmakers belong.

The pair’s behaviour during their oath-taking—especially their pronunciation of the word “China” in a way used by Japanese in imperial days—offended more than just the Communist Party’s supporters in Hong Kong. But many people worry about what they see as the NPC’s attack on Hong Kong judicial independence. The justice secretary, Rimsky Yuen Kwok-keung, who had previously said that he hoped the case could be resolved by Hong Kong’s courts on their own, denied that the territory’s legal reputation would suffer. But lawyers are planning to stage a protest march on November 8th.

The court considering the government’s case against the two legislators must now take into account the NPC’s ruling. This would mean the lawmakers could not take their oaths again. Their attempts to do so have caused stormy scenes in Legco, where pro-establishment legislators have a (gerrymandered) majority. On November 3rd six security personnel were taken to hospital after mêlées broke out in the chamber. The central government and its supporters in Hong Kong hope that the NPC’s decision will end such chaos. It may get worse, however, on the streets.