THE JUDGE LOOKED UP ONLY ONCE from the paper-clipped stack of documents, to ask the accused if he understood his sentence. Park Jeong-geun, convicted in November 2012 of violating South Korea’s National Security Law (NSL) and aiding North Korea, answered politely that yes, he understood that he had been given a suspended sentence of ten months’ imprisonment and two years’ probation.

Before reading the verdict, the judge had listed dates on which Park, a 24-year-old photographer, had retweeted messages from North Korea’s state media, acts that were held to be in violation of the NSL. Park had argued that his tweets, including one that read “Long Live Kim Jong-il!”, were sarcastic, intended to make fun of a humourless regime. But this found no favour with the court. “Their claim that I’m benefitting the North is ridiculous,” said Park outside the courtroom after receiving the sentence.

Under the NSL, it is illegal for a South Korean to do anything deemed beneficial to any anti-government organisation. This specifically includes recognising North Korea—officially considered an enemy by South Korean policy—as a political entity. The combat phase of the Korean War ended with an armistice agreement in 1953, but no peace treaty was ever put in place; the two countries technically remain at war. While supporters say the NSL is necessary to protect a fragile peace against the North Korean threat, critics say it is a vaguely worded prohibition that is really meant to stifle dissent within the country.