PARIS — Three years ago, after the suicide of a popular actress who had been bullied via the Internet, South Korea introduced a radical policy aimed at stamping out online hate. It required contributors to Web portals and other popular sites to use their real names, rather than pseudonyms.

Last month, after a huge security breach, the government said it would abandon the system. Hackers stole 35 million Internet users’ national identification numbers, which they had been required to supply when registering on Web sites to verify their identities.

The South Korean experience shows that “real name” policies are a lousy idea, and privacy threats are only one reason. Online anonymity is essential for political dissidents, whose role has been highlighted in the uprisings in the Arab world, and for corporate whistle-blowers. In the United States, the Supreme Court has found a constitutional basis for protecting anonymity.

Why, then, are the calls for restrictions on Internet anonymity growing?

Last month, Interior Minister Hans-Peter Friedrich of Germany said bloggers should disclose their true identities. He cited the case of the Norwegian terrorist suspect Anders Behring Breivik, who had professed admiration for a blogger who wrote under the pseudonym “Fjordman.”