The Hong Kong High Court on Friday sentenced the first person convicted under the National Security Law for Hong Kong to nine years in prison, saying that the defendant's preplanned act caused "grave harm" to society.

Leon Tong Ying-kit, who displayed a flag with a secessionist slogan and rammed into police officers with a motorcycle during a protest last year, was sentenced to six-and-a-half years for inciting secession and eight years for terrorist activities.

Some of his time will run consecutively, resulting in a total term of nine years.

Three judges designated for national security cases said in a written judgment that the overall term sufficiently reflects the defendant's culpability and society's abhorrence of the offense, and his jail term serves a deterrent effect upon society.

In a demonstration on July 1 last year, the second day of the implementation of the National Security Law for Hong Kong, the now 24-year-old defendant broke through several police cordon lines and injured three police officers with his motorcycle, which carried a flag bearing a secessionist slogan used during the social unrest of 2019.

The court said the slogan had a secessionist meaning and the way in which the defendant displayed the flag was clear proof that he intended to attract public attention. "The date, the time, the place and the manner were deliberately picked for attracting public attention."

The court also determined that the defendant carried out terroristic activities by crashing into three police officers, with a view to disrupt public order to pursue a secessionist political agenda. The act not only jeopardized public safety and security, but also caused grave harm to society.

Although the defendant's lawyer pleaded for mitigation for various reasons, noting the defendant showed remorse and is of good character, the court noted that the defendant pleaded not guilty to two of the offenses.

Barrister Lawrence Ma Yan-kwok said the sentence in the case has a deterrent effect and conveys a clear message to the public that incitement to secession is a serious crime regardless of its form.

Ma stressed that the judges' decision was appropriate and reasonable, showing that they have a deeper understanding of the legislative background and original intent of the law. The sentence has important precedence value for similar cases, he said.

Hours before the sentence was delivered, citizens waited in the court to hear the outcome. Around a dozen police officers stood guard outside the court building after it was learned that judges handling the case received death threats for convicting the defendant on Tuesday.

Several other high-profile cases under the National Security Law for Hong Kong will be heard in court in the next few months. They include the case of Jimmy Lai Chee-ying, who was charged with two national security offenses, and the case of 47 participants of an illegal primary election, who were charged with conspiracy to commit subversion.