Is it illegal to create a mobile app which tracks a user for some purpose?
<p>Can a mobile app track a user using GPS/location services running in the background, and do something when a user is found in a particular location?  Assuming that the app clearly tells the user that it will do this?</p>

<p>A colleague said that this is illegal because there is a court ruling that no one (software/app) can track a user's location in the background, but rather can only use location when the user is actively using the app.  Is this correct?</p>

<p>After googling I found one ruling that "warrantless tracking is not allowed."  Is this applicable?</p>

<p>It is hard to prove a negative, but no - there is not rule that an app cannot track a user while the app is in the background.</p>

<p>Almost every GPS-function app on every smart phone does the very thing you are talking about.</p>

<p>The "warrantless tracking" ruling you found applies to the admissibility of evidence collected by those means in a trial.  Unless your client is a law enforcement agency it has no bearing on the use of an app.</p>

<p><a href="https://law.stackexchange.com/a/3864/10">As jqning said</a>, there is no law against a background app using location data, and many smartphone apps do this.</p>

software privacy