Not all price similarities or price changes that occur at the same time are the result of price cartels. On the contrary, they are often the result of normal market conditions. For example, the prices of raw materials such as wheat are often identical, because the products are virtually identical and the prices charged by farmers all go up and down together without agreement between them. If a drought leads to a decrease in the supply of wheat, the price of all farmers involved increases. Increased consumer demand can also lead to uniformly high prices for a product with limited supply. Example: A group of competing optometrists has agreed not to participate in a Vision Care network unless the network increases reimbursement rates for patients covered by its plan. Optometrists refused to treat patients covered by the network plan, and eventually the company increased reimbursement rates. The FTC said the optometrists` deal was an illegal price deal and that its executives organized an effort to ensure that other optometrists were aware of the agreement and were complying with it. Example: Several cartel cases have challenged brokerage board rules that have limited access to multiple listing services (MLS) for advertising for homes for sale. The MLS system of combining home offers from many brokers has considerable benefits for home buyers and sellers. Early cases refuted brokerage board membership rules that excluded certain MLS brokers, with access to MLS seen as the key to home marketing. Recently, the FTC`s enforcement actions have challenged MLS policies that allow access, but more subtly favor certain types of brokerage agreements that offer consumers a cost-effective alternative to the more traditional full listing contract. For example, some brokers offer a limited service model in which a home is listed on the local MLS for a fee, while other aspects of the sale are given to the seller.

The FTC has questioned the rules of several MLS agencies that have excluded these brokers from popular home sales sites. These rules restricted how brokers could run their business and denied home sellers the benefit of having different types of offers. Antitrust laws do not prohibit professional organizations from adopting reasonable codes of ethics to protect the public. Such self-regulatory activity is for legitimate purposes and, in most cases, can be considered beneficial rather than harming competition or consumers. However, in some cases, ethical rules may be illegal if they inappropriately restrict the way professionals can compete. For example, a binding code of ethics preventing members from competing on the basis of price or under conditions other than those developed by the trading group may constitute an inappropriate restriction of competition. . . .