Of a judgment, how do &#39;substantive merits&#39; differ from &#39;formal qualities&#39;?
<p><sub>Source: pp 108-109, <em>Is Eating People Wrong? Great Legal Cases and How They Shaped the World</em> (2011) by Allan C. Hutchinson</sub></p>

<blockquote>
  <p>[...] For example, the difference between <em>Plessy</em>
  and <em>Brown</em> has nothing to do with their legal integrity as a
  matter of constitutional doctrine. It has everything to do
  with the changing currents and concerns in the contemporary
  political context. <em>Plessy</em>’s separate-but-equal dogma ceased to be a fixed point on the constitutional compass
  because it no longer enjoyed sufficient political confidence
  and public support, at least among the elite. When Justice
  Harlan in 1896 predicted in his dissent that the <em>Plessy</em> judgment
  “will, in time, prove to be quite as pernicious as the
  decision in Dred Scott,” <strong>he was talking about its substantive
  merits as a political outcome, not its formal qualities as a
  legal judgment</strong>. And he was correct.</p>
</blockquote>

<p>I do not understand the distinction by the bolded: What are the differences between   <strong>substantive
merits as a political outcome</strong>    vs  <strong>formal qualities as a
legal judgment</strong>? I do know of the distinction between law and politics; some judgments reflect judges' political opinions than real law. </p>

<p>The Common Law is not just the interpretation of the law by the courts in their judgements; it is also a creature of the society in which it lives. </p>

<p>A judge is bound by precedent and following that precedent leads to "its formal qualities as a legal judgement". However, if the precedent that must be followed was established in, say 1816, applying it to facts in 2016 may lead to an unjust outcome; post-Napoleonic ideas of justice do not always mesh with early 21st century ideas of justice. The judgement may be flawed in its "substantive merits as a political outcome" i.e. the punter's won't stand for it.</p>

<p>Remember that a court can always overturn a precedent set by an equivalent level or lower court so at this level, they have to decide if the precedent should be overturned to match current community notions of justice. For example, in the Australian Capital Territory it was recently decided that the precedent that an intoxicated person could not be criminally liable was not in line with community expectations and was overturned; creating a new precedent. Courts are cautious about doing this because <em>justice</em> is only <em>one</em> of the functions of the legal system; <em>certainty</em> is another and if you change precedents willy-nilly to give justice you reduce certainty.</p>

<p>A judge in a position where they <em>must</em> follow precedent has 3 options:</p>

<ul>
<li>He can follow the law and the losing party can appeal because the judgement is self-evidently wrong in providing justice - it will make its way up the chain of appeals until it reaches a level where the precedent can be overturned.</li>
<li>He can follow justice, the losing party can appeal because the judgement is self-evidently wrong in the law - it will make its way up the chain of appeals until it reaches a level where the precedent can be overturned.</li>
<li>He can kick it - basically say that whatever judgement he makes will be appealed so it should be moved to a court that can consider and perhaps overturn the precedent before everyone goes to the time and expense of arguing the facts.</li>
</ul>

us-supreme-court jurisprudence