The online review site Yelp can lower or raise the rating of a business depending on whether it advertises with the company, a federal appeals court ruled in a lawsuit filed by small businesses claiming Yelp used the tactic to try to extort ads from them. Yelp has denied doing that, saying it uses an automated system to cull reviews that determine ratings. The Court of Appeals for the Ninth Circuit ruled on Tuesday that even if Yelp did manipulate reviews to penalize businesses, the practice would not constitute extortion. The court said businesses did not have a right to positive reviews on Yelp, and that the San Francisco-based company can seek payments for its advertising. One of the businesses that sued, an animal hospital in California, claimed a Yelp representative said the company would hide negative reviews or place them lower on the page in exchange for advertising. The plaintiffs have not decided whether they will appeal.