By his own admission, Park Jung-geun has long been an Internet wiseguy, a young photographer and blogger with a cyber chip on his shoulder whose favorite target for satire is the North Korean government.
For months, his Twitter profile picture showed him with a near-empty bottle of whiskey in his hand, standing in front of a red-starred North Korean flag. Using the handle @seouldecadence, the 23-year-old re-tweeted posts fromPyongyang's Twitter account he deemed particularly ridiculous.
But the South Korean government wasn't laughing. Investigators recently searched Park's photo studio, copying computer hard disks and confiscating books and photographs. After five interrogation sessions, Park, a member of the local Socialist Party branch, was arrested last month on suspicion of "praising and supporting an enemy of the state" in violation of South Korea's strict National Security Law.
He was indicted last week, an action that Amnesty International branded "ludicrous."
The law, enacted in 1948 at the establishment of the Republic of Korea, was aimed at defending the fledgling South Korean government against espionage and other threats from belligerent North Korea, whose capital, Pyongyang, is just 120 miles northwest of Seoul, the distance between Los Angeles and San Diego. The two Koreas would go to war two years later.
Decades later, under hard-line South Korean President Lee Myung-bak, the law is being used to police the Internet for so-called suspicious political thought. On occasion, it has swept up South Koreans like Park who have joked on Twitter; security officials take particular aim at online postings deemed sympathetic to Pyongyang.
The United Nations Human Rights Commission and organizations such as Amnesty International have called for the law to be scaled back or even repealed, insisting that its broadly written provisions are employed to silence nonthreatening political opposition.
"It's had a chilling effect on critics of the government's North Korea policies," said Rajiv Narayan, East Asia researcher for Amnesty International. "The message to those who speak out is: We don't like the way you think and we will use the National Security Law to make sure you know we don't like it."
The number of National Security Law cases has risen dramatically under Lee, elected in December 2007 on a platform that called for getting tougher on North Korea. In 2007, 39 South Koreans were interrogated on suspicion of violating the National Security Law. In 2010, 151 people were questioned.
Prosecutions for online postings perceived to be pro-North Korean also have dramatically risen, from five in 2008 to 82 in 2010, according to the government's statistics, and in the first 10 months of 2011, authorities deleted 67,300 Web posts deemed to be North Korea-friendly, up from 14,430 in 2009.
Proponents of the law insist that it serves as a crucial defense against the North and has new resonance in the uncertain times after the ascent to power of Kim Jong Un, son of the late dictator Kim Jong Il, and a political unknown.
"Critics always argue about human rights, but the real focus should be the dangers presented by the North's regime," said Song Dae-sung, president of Seoul's conservative Sejong Institute.
He noted two deadly attacks by North Korea in 2010: the sinking of a patrol boat and the shelling of a South Korean island. (The North has denied any responsibility for the sinking.) Within South Korea, Song said, live 30,000 North Korean sympathizers. "Many try to connect with the North," he said. "We need this law."
But even Lee says he can see how the law could be unpopular. In a recent interview with National Public Radio, he defended South Korea's need for the law, but added with a laugh, "I recall when I was in college; I would be the one who would call for the abolishment of such laws."
While in custody, Park last month wrote a letter to the president. "My tweets considered as praising the North Korean regime were jokes, but I am not going to decrypt all the jokes and metaphors of my tweets, because you're not doing justice to your satire if you end up making an excuse for it," said the letter, posted on a South Korean blog. "I am just a young man tormented by the state."
Scholar and online bookseller Kim Myung-soo in the city of Suwon is another South Korean whose life has been altered by the National Security Law. Since 2007, he has battled charges under the law that he "aided the enemy" by marketing hard-to-find North Korean literature.
Few National Security Law cases have dragged on as long as Kim's. The 56-year-old father of three says he has endured a psychological hell defending himself against a government-imposed scarlet letter that has forced him to close his business.
As a young man, Kim was a political activist, protesting South Korea's military rule. After democratic elections were held in 1987, Kim bounced around for years, working odd jobs before eventually pursuing his first love: the literature of the Korean peninsula, north and south.
In 2003, with a master's degree in modern poetry under his belt, he opened the online business Dragon Books, selling social science texts and about 4,000 North Korean titles to earn money while researching his PhD thesis.
Four years later, he was arrested at the home he shared with his mother. Of 300 confiscated books, only 20 pertained to North Korea, he said. "I knew it was dangerous, but I didn't believe it was wrong," he said of his commercial venture. "I felt these books should be circulated among more people."
Last year, a three-judge panel found Kim not guilty. The judges ruled that there was no proof Kim had tried to benefit the Pyongyang regime with the sale of the books, which were also available at major bookstores and at the National Assembly's library. He was, the judges said, simply a scholar who researched and sold North Korean literature.
But prosecutors have appealed the decision to a federal court in Seoul, so now Kim must appear for a review of the verdict. If the first court is reversed, he faces up to seven years in prison.
Not all National Security Law cases end up in indictments. Four in 10 requests for arrest warrants from 2008 to 2010 were denied by judges, according to statistics gathered by Amnesty International.
But even being investigated under the law can exact a social and psychological price.
"People are left to pick up the pieces," said Narayan of Amnesty International. "The bookseller's life has been placed on hold, and for what? Selling books already available to the public? How does that jeopardize national security?"
The unrelenting pressure, Kim says, has made it impossible for him to concentrate on his thesis, and the ongoing government scrutiny has prevented him from winning a job as a college lecturer. Divorced and without an income, he borrows money to keep his three daughters in school.
He can't sleep at night and acknowledges that he drinks too much soju, often starting before dawn. He says alcohol deadens the pain.
His plans in limbo, Kim sat at lunch recently at a restaurant in Suwon, 20 miles south of Seoul. His food untouched, his face red with drink, he looked forlorn. "In South Korea," he said, "once the National Security Law has been applied to you, there is no escape."
For his part, Park has gone on the offensive.
Days before being indicted, figuring his arrest was imminent, he tweeted: "Now that this has happened, I am going to make fun of the prosecutor.... Hurray for Kim Jong Il!"
Jung-yoon Choi of The Times' Seoul bureau contributed to this report.