Why doesn&#39;t the 4th Amendment apply to traffic stops?
<p>Police have to search and seize your documentation in order to successfully execute a traffic stop.  Isn't this a violation of the 4th Amendment?</p>

<p>The fourth amendment <em>does</em> apply to traffic stops.</p>

<p>In general, they are a violation of the fourth amendment in the absence of <em>reasonable suspicion</em> or <em>probable cause.</em>  Even then, there are some circumstances in which suspicionless stops are acceptable to the Supreme Court, most notably in roadblock-style checkpoints for enforcing sobriety or immigration.  See, for example:</p>

<ul>
<li>Michigan Department of State Police v. Sitz (<a href="https://en.wikipedia.org/wiki/Michigan_Department_of_State_Police_v._Sitz" rel="noreferrer">on Wikipedia</a>)</li>
<li>United States v. Martinez-Fuerte (<a href="https://en.wikipedia.org/wiki/United_States_v._Martinez-Fuerte" rel="noreferrer">on Wikipedia</a>)</li>
</ul>

<p>Most traffic stops, however, occur after an officer observes a traffic violation.  This gives the officer the necessary justification to detain the motorist.  Wikipedia says:</p>

<blockquote>
  <p>A brief, non-custodial traffic stop is considered a "seizure" for the purposes of the 4th Amendment and must therefore be supported by reasonable suspicion or probable cause.</p>
</blockquote>

<p>(Source: <a href="https://en.wikipedia.org/wiki/Reasonable_suspicion#Traffic_stops" rel="noreferrer">https://en.wikipedia.org/wiki/Reasonable_suspicion#Traffic_stops</a>)</p>

<p>Also:</p>

<blockquote>
  <p>In constitutional law in the United States, a traffic stop is considered to be a subset of the Terry stop; the standard set by the United States Supreme Court in Terry v. Ohio regarding temporary detentions requires only reasonable suspicion that a crime has occurred or is about to occur.</p>
</blockquote>

<p>(Source: <a href="https://en.wikipedia.org/wiki/Traffic_stop#United_States" rel="noreferrer">https://en.wikipedia.org/wiki/Traffic_stop#United_States</a>)</p>

<p>You can also read more about Terry v. Ohio <a href="https://en.wikipedia.org/wiki/Terry_v._Ohio" rel="noreferrer">on Wikipedia</a>.</p>

<p>You may disagree with the Supreme Court on the question of whether suspicionless sobriety or immigration checkpoints <em>should be</em> allowed under the fourth amendment, but the way the system works, such stops <em>are</em> allowed under the fourth amendment simply because the Supreme Court has said so.</p>

united-states traffic fourth-amendment