As early as in his high school days, Hermon Lagman who was student council president and editor-in-chief of the school paper, showed the qualities of a principled and uncompromising student activist when he protested and editorialized irregularities in the results of the competency examinations for graduating students.
In college, he led and organized rallies and demonstrations, and expressed his nationalist views as a senior editor of the Philippine Collegian and as editor-in-chief of the Law Register, official organ of the law students at the University of the Philippines.
When he passed the bar in 1971, he became a militant advocate of labor rights, offering his services free especially to workers pursuing cases of illegal layoffs and unfair labor practices. He was a volunteer lawyer of the Citizens'Legal Aid Society in the Philippines and a founding member of the Free Legal Assistance Group.
Lagman was among the lawyers arrested after the declaration of martial law in 1972. He was kept in prison for two months without charges. From detention, he wrote to his mother Cecilia:
"At sunrise today, while standing idly in the morning cold, I saw two sparrows perched together…. (They) looked at us human beings here, and I looked at them. They seemed to have more understanding than some men…. At noon today, two clients came…. They cried…. I always dream here of all of you. We have a surfeit of energy for dreams."
He was arrested again in 1976 but released on the same day. At that time, labor groups had grown increasingly militant, staging pickets and strikes and resisting repressive martial law edicts. Lagman was legal counsel to many of these labor unions, notably the Kaisahan ng Malayang Manggagawa sa La Tondeña Inc. which spearheaded the historic first open defiance of the martial law ban on strikes and other mass actions.
On May 11, 1977, Lagman and his associate Victor Reyes left Quezon City to attend a meeting in Pasay City when they disappeared. Someone who refused to identify himself called Lagman's mother to say that he had been abducted. Searches and inquiries by relatives and friends in military camps and known detention facilities have failed to ascertain the fate and whereabouts of the two victims of enforced disappearance.
Hermon C. Lagman showed a deep and abiding commitment to the causes he espoused, and a fearlessness in living such a commitment. Said his mother: “…My son, although outwardly gentle and unassuming, was an angry young man. But his anger was not the mock anger of a showman, but the strong, silent rage of a warrior.”