The effort to create a top-level domain suffix for adult Web sites has failed, for the third time (HT: X3). ICANN voted 9-5 to defeat the proposal, which was roundly opposed by an unlikely alliance of religious groups and the adult entertainment industry.

The proposal would have created a new “.xxx” suffix that would have allowed voluntary participation of adult content providers. Many in that line of work are concerned that such a voluntary program could e mandatory, “pushing them into a so-called online ghetto.”

Religious groups are concerned that such a voluntary program would simply legitimate pornographic content on the Web without effectively segmenting objectionable content from the rest of the Internet.

We’ve talked before about options for self-regulation that could function well in place of a dedicated domain suffix, such as an NSFW (not safe for work) HTML attribute.

But as long as the “.xxx” domain proposal includes a voluntary “opt-in” for adult sites, don’t expect the unlikely alliance of religious activists and pornographers to dissolve.