Last December, Mr. Le was arrested after he wrote a column for the BBC's website in which he argued for a new constitution without a guarantee of a Communist Party monopoly on power. He regularly blogs on rights issues, and he has participated in protests against Chinese territorial claims to sovereignty over South China Sea islands also claimed by Vietnam.

The supposed crime for which Mr. Le is being charged is tax evasion, an alibi Hanoi has used in the past to incarcerate dissidents. A tax-law conviction would allow Hanoi to jail this inconvenient man for up to seven years while claiming he is not a political prisoner. Hanoi may be particularly sensitive about preserving that fiction because Mr. Le also has a connection to Washington.

In 2006-07, Mr. Le held a congressionally funded fellowship at the National Endowment for Democracy, where he researched the role of civil society in new democracies. He was arrested four days after returning to Vietnam in 2007 and freed several months later after intense U.S. pressure.

American lawmakers are again voicing their displeasure at Mr. Le's latest run-in with authorities. Twelve Representatives signed a letter to Prime Minister Nguyen Tan Dung last month calling for Mr. Le's release and warning that Hanoi's "continuing agenda to crack down on its citizens' basic freedoms will dampen diplomatic relations between our countries."

That's a potent threat since Hanoi is eager to cultivate better ties with the U.S. as a counterbalance to China's growing assertiveness in the region. The regime has in the past responded to U.S. criticism with the early release of some dissidents and other putative improvements in human rights, and we hope it will do the same for Mr. Le. But that will merely be a gesture to fend off diplomatic embarrassment unless the Communist Party respects the growing desire among Vietnamese citizens for a greater say in their government.

The Wall Street Journal - July 9, 2013