A lawmaker from the ruling Grand National Party highlighted the obvious when he showed how it is relatively simple for users in South Korean to access sites blocked by the South Korean government:

He said the law "stipulates that access to pro-North Korean websites whose contents run counter to the National Security Law could be banned. Under these laws, access to about 50 [North Korean] websites has been banned by police and the Korea Communications Commission. But the reality shows that the ban is ineffective."

In 2003-2004, North Korea declared a plan to strengthen contact with South Korea through the Internet. As controversy heated up in South Korea, Seoul in November 2004 blocked major North Korean websites.

The Korean government also uses the filters to block to restrict access to pornography, gambling and other restricted sites using the 2001 “Internet Content Filtering Ordinance” requiring Internet service providers to block restricted websites. In July, websites determined to be distributing malware in the distributed denial of service (DDoS) attacks were also blocked by the Korean Government.

CNN: Seoul blocks beheading video (June 25, 2004)

The Guardian: South Korea wants to gag the noisy internet rabble (October 8, 2008)

OpenNet Initiative: South Korea