ABSTRACT
A market consists of products which are close substitutes, or so it is said. Yet there are numerous examples where competition law markets do not consist of products which are substitutes, or interchangeable in use, or even in the same "market". One example where markets are not confined to close substitutes is so-called "aftermarkets". These consist of products that are not physically interchangeable, but are complements. An aftermarket can arise where a primary hardware product needs consumables and after-sales services. Under some assumptions, the physical product and the consumables can be in the same relevant product market and not different ones. The distinction between retail and wholesale is widely accepted. Yet the treatment of "functional" markets is not often straightforward. The indirect constraints approach has major implications for market definition and competitive analysis. It qualifies the proposition that market definition should start with the product at the heart of a competition claim.
