Litigation. Whereas some companies acquiesce to a troll's demands, others go on the offensive by challenging the patents themselves, for example by finding prior art that calls into question their patentability. They may also broadly challenge whether the technology in question is infringing, or attempt to show patent misuse. If successful, such a defense not only wins the case at hand but destroys the patent troll's underlying ability to sue. Knowing this, the patent troll may back down or lessen its demands. Early settlement. An early settlement is often far less expensive than litigation costs and later settlement values. Patent infringement insurance. Insurance is available to help protect companies from inadvertently infringing a third party's patents. Defensive patent aggregation, the practice of purchasing patents or patent rights from patent holders so they don't end up in the hands of an individual or enterprise that can assert them. Increasingly aggregations are focused on purchasing patents and patent rights off the open market, or out of NPE assertion and litigation, which directly impact the businesses of the aggregation's members. The aggregator then provides members a broad license to everything it owns in exchange for an annual fixed-fee. Defensive aggregators purchased 15% of all brokered patent sales in 2014. Action for unjustified threats. In Australia, the UK and other countries, a legal action may be brought against anyone who makes unjustifiable threats to begin patent infringement proceedings. Concerning the Australian threats provisions, Lisa L. Mueller says that "if a patent troll is found to have engaged in a threat, the only way it could defend itself against an injunction or an award of monetary damages would be to commence patent infringement proceedings and have the court find that infringement occurred." Bounties. Monetary bounties have been offered to the public to find prior art or provide other information, such as arguments showing the obviousness or material defects in a patent application, that would invalidate a patent troll's patents. This tactic has been used not only against the patent in question but also against other patents held by the patent troll in order to undermine its business model. See also Copyright troll Cybersquatting Patent monetization Patent privateer Patent war Rent-seeking Stick licensing Strike suit Submarine patent Trademark troll Wright brothers patent war References Further reading Christian Helmers, Brian Love and Luke McDonagh, 'Is there a Patent Troll Problem in the UK?,' Fordham Intellectual Property, Media