Tong Ying-Kit arrives at court on July 6, 2020 in Hong Kong.
CNN  — 

Hong Kong on Wednesday began the trial for the first person charged under its controversial national security law, which has transformed the city’s political landscape since it was imposed by Beijing last year.

Tong Ying-kit, 24, pleaded not guilty to two charges of inciting secession and terrorism activities after allegedly driving his motorbike into a group of police officers and injuring three at a pro-democracy protest last July.

He was allegedly carrying a banner that read “Liberate Hong Kong” at the time – grounds for inciting secession under the new law, prosecutors said.

Tong also faces an alternative charge to the terrorism count of dangerous driving causing grievous bodily harm, to which he also pleaded not guilty.

The wide-ranging security legislation, which criminalizes secession, subversion, terrorist activities, and collusion with foreign forces, was introduced on June 30, 2020, and carries with it a maximum sentence of life imprisonment.

Police officers stand guard as Tong Ying-kit arrives at a court in Hong Kong on June 23.

The seemingly vague parameters of the law have provided authorities with sweeping powers to crack down heavily on government opponents. Protesters and opposition leaders have been arrested under the law, while others have fled abroad in a slow exodus. The city’s highly popular anti-Beijing tabloid, Apple Daily, announced its closure Wednesday, after the paper’s assets were frozen under the national security law and several of its senior editors arrested.

Under the provisions of the law, Tong’s 15-day trial is being held without a jury, marking a significant departure from Hong Kong’s previous legal system.

Here’s what you need to know about the law – and how we got here.

What is the national security law?

The law criminalizes political dissent and offenses that challenge Beijing’s rule over semi-autonomous Hong Kong.

But the offenses are vaguely defined and wide-ranging; for instance, vandalizing public property or government premises – like protesters did in 2019 during massive demonstrations – are now considered terrorist activities.

Calling for Hong Kong independence now counts as a crime under “secession,” which is what Tong is charged with.

At court last July, Tong’s lawyer argued the interpretation and meaning of his “Liberate Hong Kong” banner is subjective, and it does not necessarily mean inciting secession or wishing to change the legal status of Hong Kong.

As the first trial under the security law, Tong’s case will be key in determining whether certain pro-democracy slogans will be deemed illegal – and will set a benchmark for how Hong Kong courts interpret the law and its provisions going forward.

The Hong Kong legal system, heavily influenced by British common law, has relied on trial by jury throughout its history. A 2003 government report noted that trial by jury was one of the “key features of the Hong Kong legal system.” But under the national security law, Beijing can take over national security cases in special circumstances – and if it involves “state secrets or public order,” it can mandate a closed-door trial with no jury.

The law also dramatically broadens the powers of local and mainland Chinese authorities to investigate, prosecute and punish dissenters, while granting mainland security agents the power to operate openly in Hong Kong for the first time.

Other provisions include the introduction of “national security education” in schools, stronger government “management” of foreign news media and NGOs, greater wiretapping abilities for police, and more.

Why is it happening now?

The national security law is not a new concept – but it was passed under unique circumstances that marked a turning point for the city.

Beijing had been asking Hong Kong to pass a national security law since the former British colony was handed back to China in 1997. But the local government backed down from its previous legislative attempts after facing fierce public opposition and protests, much to China’s frustration.

This changed in 2019. Protests over a separate bill, which would have allowed suspects in Hong Kong to be extradited to mainland China, evolved into a mass pro-democracy, anti-government movement that lasted more than six months. Demonstrations often grew violent, with near-weekly clashes between protesters and police, who deployed tear gas and water cannons.