Google has developed a so-called browser "plugin" for Internet Explorer, Firefox and Google Chrome that makes the opt-out persistent. Google has not developed a plugin for Safari. The advice Google gave Safari users follows:
"While we don't yet have a Safari version of the Google advertising cookie opt-out plugin, Safari is set by default to block all third-party cookies. If you have not changed those settings, this option effectively accomplishes the same thing as setting the opt-out cookie."
Later Google said it would will cooperate with any investigations.
"We will of course cooperate with any officials who have questions," said Chris Gaither, a spokesman for Google, which has acknowledged it placed the advertising cookies on Safari after opening a connection to give signed-in users access to a Google function. "But it's important to remember that we didn't anticipate this would happen."