Although the government says the software is aimed at blocking violence and pornography, users who have tried it say it prevents access to a wide range of topics, from discussions of homosexuality to images of comic book characters such as Garfield the cat.

Chinese authorities rarely feel compelled to justify their tight controls on the world’s largest population of Internet users. They are quick to block content challenging the ruling Communist Party’s positions on democratic reforms, religious freedom and policies toward Tibet.

Put on the defensive, state broadcaster CCTV announced on its noon news program Thursday that a “vast number of parents and experts” had endorsed the “Green Dam-Youth Escort” filtering software that must be packaged with all computers sold in China from July 1.

The official Communist Party newspaper Guangming Daily ran an almost identical report and praised the software as a breakthrough in the drive for “civilized Internet management and access.”

The government has told computer makers the software must either be installed on the hard drive or enclosed on a compact disc. PC makers will be required to tell authorities how many computers they have shipped with the software, which is made by a Chinese developer under contract with the government.

Many industry experts have privately questioned the security of computers and stored information exposed to the software. The Washington-based Computer & Communications Industry Association has said that while blocking pornography is understandable, the technology can easily be expanded into more general censorship.

“The main difference is that it takes censorship down to the level of the individual computer,” said Rebecca Mackinnon, a professor at the University of Hong Kong who studies censorship in the Chinese media and online.

That step “very directly affects the individual, and what the individual can do on their computer, how they interface with the Internet,” Mackinnon said.

Although porn sites are initially targeted, the program could be used to block other Web sites, including those based on keywords rather than specific Web addresses. Its developer said users could disable blocking of any site or even uninstall the software altogether.

A Ministry of Industry and Information Technology official went on CCTV Wednesday night to deny claims that the software incorporated monitoring or information-gathering functions.

“If there is sexual, violent or other sorts of content unsuitable for young people, then that content will be blocked,” said Chen Ying, vice director of the ministry’s department of software services industry.

However, the software requirement has prompted widespread derision among China’s more than 250 million Internet users, who either accept government controls or have learned to evade them.

Users also mocked a temporary block on networking and image-sharing Web sites such as Twitter and Flickr last week over the 20th anniversary of the bloody crackdown on Tiananmen Square pro-democracy protests. An earlier attempt to ban foreign video content from Chinese sites fizzled with little fanfare.

The new software’s blocking of content about homosexuality prompted a letter of protest from a coalition of Chinese advocacy groups representing gays and AIDS sufferers in the country.

Such content is crucial for psychological and emotional health, and it is “absolutely reasonable and beneficial, as a result, to see the sites accessible over the Internet,” the groups said in an open letter e-mailed to journalists.

The move to require the new software “is turning out to be more controversial and unwelcome than decision-makers would like to believe,” the official English-language newspaper China Daily said in an editorial Thursday under the headline “Questionable Move.”

Public agencies in Ohio are among the latest to open accounts on online meeting sites in an effort to reach people who may have a sexually transmitted disease and need medical care.

Cleveland’s health department opened accounts on two sites this week, and Cincinnati has plans to start an online effort in a couple of months. Columbus Public Health established a presence a year ago on Manhunt, a social networking site for gay men, and has since added other popular sites.

Debra Mullen, who handles online notifications for Columbus Public Health, contacted a man a year ago who did not know he had syphilis. She heard from him again this week.

“He got treatment and now is asking whether he needs any follow-up,” she said.

Traditionally, health departments have used letters and telephone calls to set up preferred face-to-face meetings with the partners of infected people who visit their clinics, test positive for a sexually transmitted disease, and reveal their partners’ names to health officials.

But with the Net, the encounters may occur between people who know only each other’s online names. Even with that small piece of information, health officials can go to the site, send a message to someone’s partner, and advise him or her to contact health officials and provide contact information.

Daniel Pohl of Howard Brown Health Center in Chicago recalls two instances where online notification has done more good than expected.

“One client I was in contact with over a couple of months was an escort. I was able to get him to come in for syphilis testing, and he was infected,” said Pohl, the center’s manager of disease intervention services. “He was treated for that, but was too afraid to get tested then for HIV.”

Over time, the man agreed and tested positive for HIV a year or so ago when he was 19, Pohl said. “He not only became very involved with his own care, but also got involved with a program that helps other young people with HIV.”

Pohl said another man who lived with an emotionally abusive male partner was notified and tested negative for HIV and syphilis, but agreed to see a counselor in the center’s domestic violence program.

“Sometimes the person on the other end of the e-mail may be completely isolated from support services, and this may help them in many ways,” Pohl said.

The National Coalition of STD Directors, consulting with the Centers for Disease Control and Prevention, developed guidelines in 2007 to help public health departments create profiles for confidential online notification. Health officials say the notification cost is minimal – a few thousand dollars for a computer and DSL line dedicated to the program.

Rachel Kachur, a researcher with the CDC’s STD prevention division, said she is encouraged more health departments are moving to online notification, but the work is not happening fast enough.

“The national guidelines help by giving local areas a jumping off point where they can tweak them to fit their needs,” she said. “But the goal is to get everyone doing this.”

Health departments in San Francisco, Washington, D.C., and Massachusetts were among the first to begin using social networks to reach a possibly infected person. The Web sites typically used cater to gays and bisexuals, such as Manhunt and Adam4Adam, but some officials hope to eventually reach the heterosexual population as well.

Cleveland, which has seen a rise in syphilis, started a presence on Manhunt and Adam4Adam this week, said David Merriman, project coordinator overseeing HIV/AIDS services for the city.

“Our goal is to also be on sites like Facebook where we could reach broader populations, including heterosexual adults and adolescents who wouldn’t use sites like Manhunt,” Merriman said.

In Massachusetts, the state health department has reported a good response since initiating partner notification on Manhunt in 2006. Kevin Cranston, director of the department’s infectious diseases bureau, says well over 50 percent of those the agency contacted online responded, with some getting department-documented medical evaluation and treatment and others saying they would seek medical evaluation on their own.

The letter demands that Knox County Schools, Metro Nashville Public Schools, and the Tennessee Schools Cooperative unblock the Internet filtering category designated “LGBT” so that students can access political and educational information about LGBT issues on school computers.

“When I found out about this web filtering software, I wasn’t looking for anything sexual or inappropriate – I was looking for information about scholarships for LGBT students, and I couldn’t get to it because of this software,” said Andrew Emitt, a 17-year-old senior at Central High School in Knoxville, in a statement released by the ACLU.

“Our schools shouldn’t be keeping students in the dark about LGBT organizations and resources,” Emitt said.

In its letter, the ACLU gives the districts and the Tennessee Schools Cooperative until April 29 to come up with a plan to restore access to the LGBT sites or any other category that blocks non-sexual websites advocating the fair treatment of LGBT people by the beginning of the 2009-2010 school year.

If that deadline is not met, the ACLU will file a lawsuit, the letter warned.

“Students at Knox County and Metro Nashville schools are being denied access to content that is protected speech under the First Amendment as well as the Tennessee state constitution,” said Tricia Herzfeld, Staff Attorney with the ACLU of Tennessee.

“This kind of censorship does nothing but hurt students, whether they’re being harassed at school and want to know about their legal rights or are just trying to finish an assignment for a class.”

The Internet filtering software used by Knox County and Metro Nashville school districts blocks student access to the websites of many well-known national LGBT organizations, including: Parents, Families, and Friends of Lesbians and Gays; The Gay Lesbian Straight Education Network; the Human Rights Campaign; The Gay and Lesbian Alliance Against Defamation; Dignity USA; Marriage Equality USA; and the Religious Coalition for the Freedom to Marry.

In its demand letter, the ACLU notes that websites that urge LGBT persons to change their sexual orientation or gender identity through so-called “reparative therapy” or “ex-gay” ministries – a practice denounced as dangerous and harmful to young people by such groups as the American Psychological Association, the American Psychiatric Association, the American Medical Association, and the American Academy of Pediatrics – can still be easily accessed by students.

“One of the problems with this software is that it only allows students access to one side of information about topics that are part of the public debate right now, like marriage for same-sex couples,” said Karyn Storts-Brinks, a librarian at Fulton High School in Knoxville.

“Students who need to do research for assignments on current events can only get one viewpoint, keeping them from being able to cover both sides of the issue.  That’s not fair and can hinder their schoolwork,” she said.

No federal or state law requires school districts to block access to LGBT sites.  Tennessee law only requires schools to implement filtering software to restrict information that is obscene or harmful to minors.

About 80 percent of Tennessee public schools, including those in the Knox County and Metro Nashville districts, use filtering software provided by Education Networks of America, and the software’s default setting blocks sites ENA categorizes as LGBT the ACLU said.

The ACLU said it believes that most of the 107 Tennessee school districts that use ENA’s filtering software keep the LGBT category blocked.  ENA blocks access to a wide category of “LGBT” sites described on the organization’s website as ” Sites that provide information regarding, support, promote, or cater to one’s sexual orientation or gender identity including but not limited to lesbian, gay, bi-sexual, and transgender sites.

“When public schools only allow access to one side of an issue by blocking certain websites, they’re engaging in illegal viewpoint discrimination,” said Hedy Weinberg, Executive Director of the ACLU of Tennessee.

“Over a hundred other school districts in Tennessee use the same filtering software used in Metro Nashville and Knox County, and we’re eager to find out whether any of those systems are also violating students’ Constitutional rights by restricting access to LGBT sites.”

The legislation, which targets hate on the Internet, has put Canada among a “sorry group of nations” that stifle dissent for political reasons, its critics told the hearing.

But supporters argued the Canadian Human Rights Act is a necessary restriction on free speech that protects vulnerable minorities.

The Canadian Human Rights Tribunal is trying to decide whether Toronto resident Marc Lemire is responsible for material posted on an electronic bulletin board frequented by far-right users.

The postings mocked Jews, blacks, Italians, gays and other minorities.

“The law should not concern itself with jokes and trivia,” lawyer Barbara Kulaszka, who represents Lemire, said in closing arguments.

“Jokes hurt too,” countered Athanasios Hadjis, who is chairing the tribunal.

“This is a law that has gone mad,” Kulaszka replied. “There is no balance in this law whatsoever.”

Lemire is arguing that sections of the decades-old Canadian Human Rights Act are unconstitutional.

Section 13, initially aimed at telephone hate messages, was extended in 2001 to cover Internet communications.

Lawyer Steven Skurka, acting for the Friends of the Simon Wiesenthal Centre for Holocaust Studies, argued the case is not about suppression of legitimate dissent.

The legislation targets only the most “poisoned” forms of expression that have no redeeming value and cause enduring harm to its victims and therefore society at large, he said.

“We support the right to offend and to be offensive,” Skurka said. “(But) hate propaganda does nothing to advance freedom of expression.”

Lemire’s freedomsite.org website, started in 1995, became the subject of a hearing in 2003, after Ottawa lawyer Richard Warman complained that postings on the site promoted hatred or could subject a group to contempt.

Lemire, 32, shut down the message board in Jan. 1, 2004, but the case has continued to wind its way through tribunal hearings, proving, his lawyers said, that legislation intended to be remedial has become a punitive instrument that can impose hefty fines.

Critics of the act also noted the tribunal has never dismissed a complaint.

Earlier in the hearing, Hadjis mused that the legislation may be outmoded in an Internet age where almost anyone can post messages and any complaint can lead to a lengthy and cumbersome process.

But Marvin Kurz, speaking for the Jewish human rights group B’nai Brith, said the Internet has not changed the harm caused by hate propaganda. Nor has it minimized the right of people to be protected from exposure to contempt and hatred, he said.

Paul Fromm, of the Canadian Association of Free Expression, called the legislation “excessive.”

Those who have fallen afoul of Section 13  – Warman has filed most of the complaints – have been poor uneducated whites who hold far right-wing views and lack sophistication in making their opinions heard, Fromm told the hearing.

“We should all have an equal right to express ourselves,” Fromm argued. “That is what the Internet has enabled us to do.”

Canada is acting like China by “slowly gagging” dissent, he said.

“Any regime that condemns jokes is pretty far gone.”

Critics have also warned that mainstream media could easily become ensnared by the act.