More than 15,000 inmates will be released next week.
They press Vietnam to revise a harsh web decree which goes into effect in a week.
Dissident veteran Communist Party members found the Social Democratic Party.
The young woman was jailed for alleged anti-state activity.
They share concerns over vaguely worded laws and regulations used to suppress online discussions.
Decree 72 is described as the worst attack on press freedom in Vietnam in two years.
The prisoner of conscience had spent 35 days protesting conditions in jail.