Speed Zone Studies and 85th Percentile Speed in Texas
<p>If you have a speeding ticket in Texas, how exactly could a Speed Zone Study help to defend against the citation?</p>

<p>If the ticket says, for example, 80 mph in a 70 on an interstate (which is the lowest possible citation in a 70 zone, according to an officer), what information from a traffic study would be sufficient to overrule such citation in Texas?  (And assume that <a href="https://law.stackexchange.com/questions/2061/is-following-the-flow-of-traffic-a-valid-speeding-defence-in-texas">the flow of traffic already contradicted the posted limit at the time of the citation</a>.)</p>

<p>Obviously, if the study were to say 80 mph, it'd be all clear, but it's more statistically likely that a study would find an 85th percentile speed to be some number between 72 and 77 mph, then what?</p>

<p>You seem to misunderstand what <em>prima facie</em> means: accepted as correct until proved otherwise.</p>

<p>The facts are that you exceeded the posted speed limit; therefore it is legally accepted that you were driving at a speed "greater than is reasonable and prudent under the circumstances then existing". </p>

<p>To overturn the prima facie assumption you must prove <em>beyond reasonable doubt</em> (for a criminal matter) or <em>on the balance of probabilities</em> (for a civil matter) that the speed at which <em>you</em> were travelling was "reasonable and prudent under the circumstances then existing". Demonstrating that other people were also driving at this speed does not show that <em>you</em> were "reasonable and prudent" because <em>prima facie</em> they were themselves not "reasonable and prudent".</p>

<p>A possible (if unlikely to succeed) defence would be to demonstrate that the combination of your driving skill, your vehicle's performance and the road conditions were such that <em>you</em> were as or more capable of avoiding a collision at 80mph as the general population is at 70mph. A professional race car driver in a high performance vehicle on a perfect driving day <em>might</em> have a chance with this.</p>

texas traffic evidence speeding prima-facie-speed-limits