Advocates of the right to be forgotten say it is unrealistic to expect Internet companies like Google and Facebook, which collect huge amounts of data on their users in order to direct relevant advertising to them, to put safeguards in place without stricter regulations.

European Union lawmakers want to establish two separate, but related, digital privacy rules. One would guarantee Internet users the right to delete pictures, writings and other data on social networks and other online forums. In theory, this is already permitted, but regulators say removal can be cumbersome and deleted material often lingers in search engines and elsewhere.

Under the proposal, search engines would have to remove the material immediately. Internet companies balk at that. They say that they generally favor giving people control over material they have posted themselves, but oppose letting Internet users demand that search engines and other sites remove information about them that has been posted by others, perhaps including official documents.

The principle of a right to be forgotten is being tested under existing laws in Spain, where the government has ordered Google to remove unflattering references to dozens of individuals who filed complaints with the Spanish Data Protection Agency. Google has refused, insisting that only publishers or courts, not individuals or search engines, should have the power to remove information, assuming that it was legally published.

A test case, involving a Spaniard named Mario Costeja who is seeking the removal of links to a newspaper notice from 1998 that his home was being auctioned after he failed to pay social security taxes, has gone to the European Court of Justice in Luxembourg. An advocate general, or legal expert to the court, is expected to issue an opinion late this month.

“Search engines should not be subject to censorship of legitimate content for the sake of privacy — or for any other reason,” William Echikson, Google’s head of free expression for Europe, wrote in a blog post on the case, noting that the newspaper announcement of the auction had been required under Spanish law.

Advocates of a right to be forgotten say different standards are needed in cyberspace because information like this is so much more readily available online than on paper, with the auto-complete functions of search engines sometimes providing negative associations even as users type in a name.