In Mr. Tong’s case, the prosecutors made clear that the sentence against him should be determined as much by the message on his banner — a popular slogan the government has deemed a call to independence — as his collision with the police.
He was sentenced to six and a half years for inciting secession and eight years for terrorism, terms that were to run partly concurrently, for a total of nine years.
Without the national security law, a person convicted of driving dangerously could have received a sentence of seven years, and of two years for assaulting a police officer. Clive Grossman, Mr. Tong’s lead defense lawyer, said they would appeal the verdict and the sentence.
The power to interpret the security law rests with Beijing, and some observers say the outcome of Mr. Tong’s trial shows that Hong Kong’s courts have less space to weigh individual rights when considering security-related charges.
“Thus far, the government has run the table on N.S.L. cases, both on key procedural matters and now on guilty verdicts,” said Thomas Kellogg, the executive director of the Georgetown Center for Asian Law. “This is not a good sign that the courts will be able to mitigate the worst elements of the N.S.L.”
Mr. Tong, 24, was a cook in a Japanese restaurant who helped provide first aid to protesters in 2019. He was the main breadwinner for his family and helped support his sister’s studies abroad, according to his lawyers.
He was arrested on July 1, 2020, after colliding with police officers while driving his motorcycle, which had a flag mounted on it that bore the slogan, “Liberate Hong Kong, Revolution of Our Times.” Three officers were injured, though not seriously, according to the court.