A landmark ruling on Hong Kong’s largest national security trial to date has set out that those who plot to subvert state power need not use force or employ criminal means to be found guilty of breaching the national security law (NSL), nor do they need to know that their tactics were unlawful.

National security judges Andrew Chan, Alex Lee and Johnny Chan laid out their reasoning in a 319-page judgement, which found 14 defendants guilty of conspiring to commit subversion while acquitting two. Thirty-one others earlier pleaded guilty to the same charge.

The judges concluded that those convicted had taken part in a plot to seriously obstruct, disrupt or undermine the duties and functions of the Hong Kong government by unlawful means with a view to subvert state power.

The court found that they had planned to indiscriminately veto any budget or public expenditure request by the government if they win a majority in the Legislative Council election in 2020, to compel the chief executive to accede to demands made by anti-government protesters or be forced to dissolve the legislature and resign.

The judges rejected arguments by defence lawyers that "unlawful means" necessitates the use or threat of force; that guilty parties must know that what they were doing was illegal; and that Legco members who veto government budgets are merely exercising their constitutional duty instead of breaking the law.

In the ruling, the judges noted that the NSL was drafted with the understanding that national security in the city could be undermined not only by force, but also by non-violent actions such as advocating Hong Kong's independence, inciting public hatred, and paralysing the work of the government and legislature.

It said limiting "unlawful means" to acts of force would be such a narrow interpretation that "would be absurd and illogical and defeat the purpose of the NSL".

The judges also swept aside defence arguments that "other unlawful means" should only include criminal acts, saying it’s “inconceivable that acts or activities by whatever forms and methods with a view to subverting the state power could be considered to be acceptable or tolerable.”

Moreover, they ruled that the defendants did not have to be aware that they were breaching the law at the time of the offence, so long as the accused had intentionally committed an unlawful act with a view to subverting state power.

“Therefore, it was irrelevant to the issue of guilt that the accused acted with a mistaken belief that his or her means was lawful; to hold otherwise would go against the purpose of the NSL,” the judges wrote.

While the judges agreed that legislators should not automatically approve government budgets, any plan to indiscriminately veto such budgets in an attempt to force the government to accept political demands would, they concluded, constitute an abuse of power that contravenes both the Basic Law and the NSL.

The court also dismissed defence claims that the offence wasn’t clearly defined because the law doesn’t provide specific definitions for "subversion" or "state power".

The judges said it was obvious that all the powers of the Hong Kong Special Administrative Region ultimately came from the Constitution and the Central People's Government, and concluded that "state power" refers to those wielded by the SAR government, including the various duties and functions it performs.

Using a dictionary definition of "subversion", the judges ruled that “a serious interference in, disruption or undermining of the performance of duties and functions in accordance with the law by the body of power of the Hong Kong Special Administrative Region… could amount to an act ‘subverting the State power’.”

As such, they found that 14 defendants had knowingly participated in the plot, with the intention of subverting state power, and therefore found them guilty.