Frank Pasquale, Rankings, Reductionism, and Responsibility. This provocative piece argues for regulation of search engines to require them to allow a right of response when a negative result for a particular person (or product?) is very high-ranked, as well as a due process-type right to an explanation when a site's ranking goes sharply down.
Though Pasquale occasionally hints at a consumer protection rationale, he focuses on the harms to the targets of searches rather than on the interests of searchers in getting balanced or accurate information. Current law, by contrast, requires plaintiffs to claim some sort of consumer harm. That's unlikely to be a winning strategy, since I have a hard time imagining Google losing users from full disclosure: "We mostly use an algorithm to rank results, but occasionally we intervene to combat what we, in our sole discretion, consider attempted manipulation of the rankings, and also we may change rankings to fulfill other objectives such as avoiding lawsuits." As with coupon settlements, such disclosure might improve Google's credibility with the few people who notice it, rather than decreasing its user base.