As the Washington Post points out, untried stem cell therapy has led to severe blindness in some patients. Although the U.S. Food and Drug Administration (FDA) won a lawsuit in June to close a Florida clinic, the whole field remains largely unregulated and science has not yet been confirmed.
According to Google's statement, the new policy will ban two treatments, involving "no biomedical or scientific evidence at all" and "no evidence of widespread clinical use in formal clinical trials". Although Google did not provide information about more specific digital terminology, the company said that advertising "has no place on our platform".
While Google is dedicated to stem-cell therapy and other similar treatments, new policies seem to apply to all untested treatments, not just these specific areas. That is, the new policy does let Google play the "ultimate arbiter" 's role again on its platform, at its sole discretion, of what constitutes or does not constitute a "Unconfirmed or experimental medical technology", and which advertising will be modest, a role that the company has been working in the past (especially in the case of YouTube).
Google will still allow for advertising research and clinical trials as long as Google follows other rules in Google's healthcare and pharmaceutical advertising policies. The company also noted that it would continue to assess ongoing research and would continue to modify its policies as needed.