Former union leader Carol Ng Man-yee, and activists Nathan Lau Chak-fung and Frankie Fung Tak-chun were the third batch of defendants in the landmark case to complete their sentences.
The trio, who pleaded guilty and served four-year-and-five-month sentences, were separately sent directly from the Lo Wu Correctional Institution and Stanley Prison to their residences in vans on Monday morning.
Asked about his feelings, Lau put on a smile and shook his head while walking towards his block.

Lau, 28, was the president of the student union at Hong Kong Shue Yan University and a standing committee member of the Hong Kong Federation of Students.
Ng, now 54, was a flight attendant at British Airways. She founded the BA Hong Kong International Cabin Crew Association and had mounted several legal challenges against the employer over wages, anti-union practices, age and sex discrimination.