FTO - Freedom to Operate
<p >A clearance search, also called freedom-to-operate search or infringement search,<sup id="cite_ref-8" class="reference" ><a href="http://en.wikipedia.org/wiki/Patent_infringement#cite_note-8" >[8]</a></sup> is a search done on issued patents or on pending <a href="http://en.wikipedia.org/wiki/Patent_application" title="Patent application" >patent applications</a> to determine if a product or process infringes any of the <a href="http://en.wikipedia.org/wiki/Claim_(patent)" title="Claim (patent)" >claims</a> of the issued patents or pending patent applications. A clearance search may also include expired art that acts as a 'safe harbor' permitting the product or process to be used based on patents in the public domain. These searches are often performed by one or more professional patent searchers who are under the direction of one or more <a href="http://en.wikipedia.org/wiki/Patent_attorney" title="Patent attorney" >patent attorneys</a>.</p>
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A clearance search can be followed by a <i>clearance opinion</i>, i.e. a legal opinion provided by one or more patent attorneys as to whether a given product or process infringes the claims of one or more issued patents or pending patent applications. Clearance opinions may be done in combination with a "validity and enforceability" opinion. A validity and enforceability opinion is a legal opinion as to whether a given patent is valid and/or enforceable. In other words, a <i>validity opinion</i> is a legal opinion or letter in which a patent attorney or patent agent analyzes an issued patent and provides an opinion on how a court might rule on its validity or enforceability.<sup id="cite_ref-9" class="reference" ><a href="http://en.wikipedia.org/wiki/Patent_infringement#cite_note-9" >[9]</a></sup> Validity opinions are often sought before litigation related to a patent. The average cost of a validity opinion (according to one 2007 survey) is over $15,000, with an infringement analysis adding an additional $13,000.<sup id="cite_ref-10" class="reference" ><a href="http://en.wikipedia.org/wiki/Patent_infringement#cite_note-10" >[10]</a></sup></p>
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The cost of these opinions for U.S. patents can run from tens to hundreds of thousands of dollars (or more) depending upon the particular patent, the number of defenses and prior art references, the length of the prosecution file history, and the complexity of the technology in question.</p>
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An <i>exculpatory opinion</i> (setting forth reasons the patent is not infringed, or providing other defenses such as prior use, intervening rights, or prior invention) is also possible.</p>