This article discusses a court decision ruling on advertisements made by eBay, in which the average eBay price for products was compared to the average in-store price with certain chains. Some stores initiated a cease-and-desist order, which was rejected in first instance by the court, but granted in appeal due to infringements on the rules of comparative advertising.
Interesting to note, according to the author, is that the definition of comparative advertising should be interpreted broadly, as in this case the advertiser (eBay) was not as such a competitor of the stores. Only the goods themselves are competitive.
The author further discusses the general conditions in relation for comparative advertising to be unlawful.