Enforcement of patents is a pivotal factor in determining whether or not the patent system performs its public role of stimulating innovation. Without the means to exclude imitators, the party who pays for the original idea or invention will, in many cases, not be able to recoup their outlays, with the result that such parties are likely to direct their investment elsewhere and invest less in research and development. Enforceability matters even if the invention embodied in a patent is not being directly commercialised by the inventing organisation. Intellectual property (‘IP’) owners will not, for example, be able to license, cross-license, or sell their IP rights, or enter into joint ventures based on those rights, if the licensee, buyer or joint venture partner has no confidence that their IP rights confer effective exclusivity over brands, ideas or creations. Furthermore, IP owners will be reticent to disclose their ideas to prospective partners if they have doubts about their ability to prevent the other party from expropriating their proposal. Direct enforcement of each and every patent does not have to occur for the patent system to be effective. All that is required for incentives to work is that people believe that infringement will be stopped if necessary.