HONG KONG — Former Hong Kong publisher Jimmy Lai began testifying Wednesday in his landmark national security trial that is widely seen as a measure of press freedom and judicial independence in the Chinese territory.

Lai, who will turn 77 next month, entered the court in a gray blazer and a pair of glasses, waving and smiling at his family members, who sat next to the city’s Roman Catholic Cardinal Joseph Zen. The Catholic raised the Bible and swore his evidence would be true in court.