<i>The findmyfriends feature on my iPhone has been 100% accurate in identifying where my friends are</i><p>My wife and I use Find My Friends quite often to keep track of our children. I&#x27;ve used it for years, so I&#x27;m quite familiar with it. Our experience is quite the opposite of &quot;100% accurate&quot;.<p>I provided more detail in this other post: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10950107" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10950107</a><p>Edit: just looked up the USA version of &quot;probable cause&quot; here: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Probable_cause#United_States" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Probable_cause#United_States</a><p>In my opinion Find My Friends does <i>not</i> meet the standard of probable cause as defined by that Wikipedia article. I&#x27;d characterize its behavior be somewhere in between &quot;reasonable suspicion&quot; and &quot;probable cause&quot;. I&#x27;ve seen the location be wrong and stay wrong for 1&#x2F;2 hour or more. And I don&#x27;t mean it can&#x27;t find a location, I mean that it is repeatedly reporting the wrong location (&quot;now&quot;) for an extended period of time.<p>Oh, and BTW following that Wiki link for &quot;reasonable suspicion&quot; says that it is sufficient for obtaining a warrant. IMO Find My Friends does meet that standard, at least as I understand it by a quick reading of Wiki.