Yonhap / AFP / Getty Images A South Korean K1 tank fires during a military drill near the DMZ in Yeoncheon, north of Seoul, on May 25, 2010

In the South Korean army, some writings of the American leftist Noam Chomsky are, literally, forbidden. Last week, South Korea's constitutional court upheld a controversial ban on 23 books that service members, under military regulations, cannot read or keep on bases. Army lawyers argued that the prohibition was a fair interpretation of the military's disciplinary code, because the literature in question sympathizes with communist North Korea and criticizes the economic systems of South Korea and the U.S. That content, in turn, could hamper the morale of service members, they said.

The plaintiffs  seven dismissed army judges who first petitioned against the book ban in 2008  contended that the policy violated rights guaranteed in the country's 1948 constitution. But judges in the high-ranking South Korean court dismissed their case in a 6 to 3 vote, ruling that the ban's scope was appropriately limited to few books and few people, and that the benefits to national security were no less important than an individual's right to access information. The decision comes after an administrative court last April ordered the Defense Ministry to reinstate one lawyer who was discharged from the army after he petitioned against the ban, while upholding the dismissal of another legal officer. (See TIME's top 10 banned books.)

The Defense Ministry instigated the ban two years ago, when army authorities stamped the 23 books as "seditious." The prohibition is based on a military-discipline code, which allows military authorities to ban more books that they consider subversive. They fall under three categories, consisting of proNorth Korea, antiSouth Korea and anti-American or anticapitalist writings. They include two volumes by Chomsky, the activist and linguist at the Massachusetts Institute of Technology, and one by Ha-Joon Chang, a well-known South Korean economist at the University of Cambridge. In his book Bad Samaritans: The Myth of Free Trade and the Secret History of Capitalism, published in 2007, Chang argues that poor countries should not embrace free trade to attain rapid economic growth  a skeptical view of unrestrained markets that was unpopular in some South Korean military circles. "The book ban was created because of an imminent need to keep soldiers alert, which is the basis for accomplishing the national army's mission," a Defense Ministry spokesman told TIME in a written statement.

In South Korea, last week's ruling reignited the debate over to what extent the legal system must uphold democratic freedoms while protecting national security. Ever since the Korean War was fought from 1950 to '53, the capitalist South has repeatedly faced threats and military attacks from North Korea, its authoritarian neighbor that allegedly torpedoed a South Korean ship last March, killing 43 sailors. That chronic tension means all South Korean men must serve for at least two years in the military, an institution with rules prohibiting soldiers from holding "subversive" documents on bases. "The book ban is a necessary evil with the tensions between the two Koreas," along with the discipline needed in the armed forces, says Kang Sung Hun, a former army legal officer.

While the armed forces give precedence to troop morale, others say the country's information laws should permit soldiers to read the same books that civilians have access to. They say South Korea's constitution guarantees its citizens freedom of expression, which lawyers have argued includes a right to know. "It's hard to accept this excessive restriction," says Lee Jong Soo, a constitutional-law professor at Yonsei University in Seoul, "on the grounds of an ambiguous concept of sedition."

Although South Korea today is a wealthy democracy, the practice of censoring books and films was frequent under the country's dictators from the early 1960s to the late 1980s  especially if those works were deemed supportive of North Korea. Park Chung Hee, the military strongman who ruled from 1961 until his assassination in '79, did just that by endowing the Korean Central Intelligence Agency, the former South Korean spy service, with generous funds to build an expansive network of informers. For years, agents ratted out dissidents and circulated anticommunist propaganda, and in 1973 even kidnapped and tried to drown Kim Dae Jung, an opposition politician who became President from 1998 to 2003 and won the Nobel Peace Prize for his reconciliation attempts with North Korea.

Chang of the University of Cambridge says that times have changed, and that simply banning a book in today's digital era cannot stop the flow of information. Bad Samaritans became a popular seller in South Korea after the 2008 policy went public. But Chang says he's perplexed as to why the army placed it on the list because he spoke favorably about South Korea's growth model, even during those politically draconian years. "Despite my reservations about his politics, I was actually saying many positive things of Park Chung Hee's development strategy," he says. "It was quite sad to see that there are still some people [in the military] who think we are living in the 1970s and '80s."

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