fact, some are able to draw on hedge funds and institutional investors to finance their patent cases). Patent "pooling" arrangements where many companies collaborate to bring their patented knowledge together to create new products are also inapplicable to patent trolls because they do not produce products. It is possible to perform offensive techniques to ward off patent trolls with the open source release of concepts preemptively to prevent patent trolls from establishing intellectual property on building block technology. A Google-led initiative, LOT Network, was formed in 2014 to combat PAEs by cross-licensing patents that fall into the hands of enforcers. Another Google-affiliated organization, Unified Patents, seeks to reduce the number and effectiveness of patent trolls by filing inter partes reviews (IPR) on patents owned by trolls. Large companies who use patent litigation as a competitive tool risk losing their patent rights if a defendant claims patent misuse. However, the misuse defense is difficult against a patent troll because antitrust violations typically involved require significant market power on the part of the patent holder. Nevertheless, manufacturers do use various tactics to limit their exposure to patent trolls. Most have broader uses as well for defending their technologies against competitors. These include: Design arounds can be a defense against patent trolls. The amount of license fee that a patent troll can demand is limited by the alternative of the cost of designing around the troll's patent(s). Patent watch. Companies routinely monitor new patents and patent applications, most of which are published, to determine if any are relevant to their business activities. Clearance search. A standard practice is to perform a clearance search for patents or pending patent applications that cover important features of a potential product, before its initial development or commercial introduction. For example, a search by Thomas Edison uncovered a prior patent by two Canadian inventors, Henry Woodward and Mathew Evans, for carbon filament in a non-oxidizing environment, (), the type of light bulb Edison wanted to develop. Edison bought the patent for US$5,000 ($ in present-day terms) to eliminate the possibility of a later challenge by Woodward and Evans. Opposition proceeding. In Europe (under the European Patent Convention), any person may initiate proceedings to oppose a European patent. There is a more limited process in the United States, known as a reexamination. As an example, Research In Motion, filed reexaminations against broad NTP, Inc. patents related to BlackBerry technology.