Police said she failed to delete it promptly.
“We still don’t know how authorities get access to IP addresses of these people arrested because they did not ask Web masters,” she said.
Sawatree Suksri, a lecturer at the law faculty at Thammasat University, said the law is ambiguous on several points, especially the use of terms “national security” and “public panic,” which are subject to interpretation.
Other analysts say the clampdown is reducing the space for public debate and hurting investors’ confidence in Thailand’s US$260 billion economy, Southeast Asia’s second largest.
“Investors who were previously unaware of the intensity of debate over Thailand’s future have quite noticeably begun to voice increasing concern,” Montesano said. “These arrests are likely to reinforce this trend.”
Because the throne is traditionally sacrosanct and open discussion of the monarchy is limited by lese majeste laws, which carry a maximum penalty of 15 years in prison, mainstream media has largely practiced self-censorship, but policing the often-anonymous world of the Internet is far more difficult.
Chiranuch said fear of prosecution may lead some surfers to consider disguising their identities or altering their IP address when visiting political web boards.
Some rights groups said the use of the computer law may have gained prominence recently because authorities may be less inclined to use its harsh lese majeste laws on Web surfers.
The computer law may be used “for the prosecution of any type of thought crime on the disingenuous pretext that the crime is one of technology rather than one of expression or of ideas,” private watchdog the Asian Human Rights Commission said.
Police, however, say it is crucial and effective.
“We don’t want to have to invoke his majesty to prosecute cases which obviously threaten national security,” said Police Lieutenant General Tha-ngai Prasjaksattru, head of the Criminal Investigation Bureau. “We don’t need to say it’s libel because we have a law that says spreading lies online is a crime.”



