What are common law cases &quot;lost in the mists of time&quot;?
<p>A respected user writes in another answer:</p>
<blockquote>
<p>Long-standing precedents whose origins are lost in the mists of time</p>
</blockquote>
<p>What are these long standing precedents, how are they known, and how can they be authoritatively understood, litigated, and ruled on, when they have been &quot;lost in the mists of time&quot;?</p>
<p>What are some examples of these precedents?</p>

<h2>Time immemorial is 1189 CE</h2>
<p>Do you know how many documents survive from 1189 CE? F#*k all, that’s how many.</p>
<p>We don’t have the original case law because, quite simply, we don’t have the original case law. In any event, “time immemorial” is simply a legal fiction stating the date to which you had to be able to trace land ownership before you had indefeasibility of title. Common law goes back <em>way</em> beyond that and even <em>way</em> beyond the Norman conquest in 1066.</p>
<p>At a certain point, it doesn’t matter. Things are done that way because things are done that way. For example, Pythagoras’ Rule (the square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two sides) was not discovered by Pythagoras. It was known to both the Babylonians and Egyptians 1,000 years before Pythagoras was born yet it will likely be Pythagoras’ Rule  for as long as  the human race endures.</p>

england-and-wales common-law precedent