What does the patent litigation piece of the Apache License mean?
<p>I am looking at <a href="https://en.wikipedia.org/wiki/Apache_License" rel="nofollow noreferrer">this</a> from Wikipedia:</p>
<blockquote>
<p>The Apache License 2.0 makes sure that the user does not have to worry about infringing any patents by using the software. The user is granted a license to any patent that covers the software. This license is terminated if the user sues anyone over patent infringement related to this software. This condition is added in order to prevent patent litigations.</p>
</blockquote>
<p>I don't follow what this is saying, can one please explain in plain english? If I have a project and make it Apache License, what does this section mean for me? As a related question, why does OpenBSD think this section makes the Apache license &quot;not free&quot;?</p>

<p>If software is licensed under the Apache license, then you can use that software under open source terms.</p>
<p>Part of the Apache license specifically grants you a patent license for the software. However, if you attempt to sue anyone, alleging that the software is infringing on patents that you own, the patent license you received is automatically revoked.</p>
<p>The part that causes this to happen is <em>&quot;If You institute patent litigation against any entity ... alleging that the Work constitutes direct or contributory patent infringement&quot;</em> then <em>&quot;any patent licenses granted to You under this License ... terminate&quot;</em></p>
<p>This clause exists to discourage people from claiming the software is infringing on their own patents, but still using a patent license for the software themselves.</p>

<p>As I understand it (and remember this is not legal advice):</p>
<ul>
<li><p>If you use software licensed under the <a href="https://www.apache.org/licenses/LICENSE-2.0" rel="nofollow noreferrer">Apache License 2.0</a>, you get a patent license for that software from its contributors.</p>
</li>
<li><p>However, if you have a patent of your own, which is allegedly infringed by the software, and you sue the software's contributors for infringing your patent, you forfeit the patent license that you received for their software.</p>
</li>
</ul>
<hr />
<p>And as for OpenBSD, <a href="https://www.openbsd.org/policy.html" rel="nofollow noreferrer">here's what they have to say about the Apache License 2.0</a>:</p>
<blockquote>
<p>Apache</p>
<p>The original Apache license was similar to the Berkeley license, but source code published under version 2 of the Apache license is subject to additional restrictions and cannot be included into OpenBSD. In particular, <strong>if you use code under the Apache 2 license, some of your rights will terminate if you claim in court that the code violates a patent.</strong></p>
<p>A license can only be considered fully permissive if it allows use by anyone for all the future without giving up any of their rights. <strong>If there are conditions that might terminate any rights in the future, or if you have to give up a right that you would otherwise have,</strong> even if exercising that right could reasonably be regarded as morally objectionable, <strong>the code is not free.</strong></p>
</blockquote>
<p>(Emphasis added.)</p>
<p>In short: since the Apache License 2.0 has conditions that might terminate your patent license in the future, it does not qualify as free under the OpenBSD definition of &quot;free code.&quot;</p>
<p>Furthermore:</p>
<blockquote>
<p>In addition, the clause about the patent license is problematic because <strong>a patent license cannot be granted under Copyright law, but only under contract law, which drags the whole license into the domain of contract law.</strong> But while Copyright law is somewhat standardized by international agreements, <strong>contract law differs wildly among jurisdictions. So what the license means in different jurisdictions may vary and is hard to predict.</strong></p>
</blockquote>
<p>(Emphasis added.)</p>
<p>So, OpenBSD also disapproves of the patent license clause because of its potential to lead to more ambiguity and unpredictability.</p>

<h2>Don't look at that ...</h2>
<p>Look at the <a href="http://www.apache.org/licenses/LICENSE-2.0" rel="nofollow noreferrer">license</a> itself:</p>
<blockquote>
<ol start="3">
<li><strong>Grant of Patent License.</strong> Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed.</li>
</ol>
</blockquote>
<p>That's what it means.</p>

software patents open-source-software