Yesterday, we reviewed the average length of the Court’s opinions – majorities, concurrences and dissents – for the years 1990 through 2003.  Today, we’re bringing the numbers up to the present day.

We noted yesterday that majority opinions seemed to have gotten slightly longer on average for the years 1990 through 2003.  For the years 2004 through 2017, majorities held steady at around the level they found in the second half of the earlier period.  Between 2004 and 2007, the average majority opinion was between twenty-two and twenty-six pages.  Between 2012 and 2016, the average was between twenty-six and twenty-eight pages.  The average majority opinion last year was 23.81 pages.

Concurrences – typically a very small data set in any given year – have not followed any consistent trend.  The average concurrence reached 5.2 pages in 2006 and 5.54 in 2009 before tailing off again in 2010 and 2011. In 2012, the average concurrence was 9.29 pages.  In 2014 and 2015, the average concurrence stayed above seven pages (7.88 and 7.22).  After a one-year anomalous spike in 2016, the average settled back down to 4.25 pages in 2017.

Dissents are clearly getting longer.  For the years 2004-2006, the average stayed steady – 9.78 pages, 9.85 pages and 8.82 pages, but beginning in 2010 (13.78 pages), the average began climbing – 16.5 pages in 2011, 10 pages in 2012, 12.56 pages in 2013, 13.57 pages in 2014, 12 pages in 2015, 13 pages in 2016 and 18.1 pages in 2017.

Is the average total page output of opinions per case increasing?  The answer is an unequivocal yes.  Between 2004 and 2009, the number was relatively steady – between thirty-five and forty every year except 2008.  But since then, the average output has been rising: 43.3 pages in 2010, 44.82 in 2011, 47.21 in 2012, 44.26 in 2013, 48.84 in 2014, 46.91 in 2015, 58.51 in 2016 and 46.16 in 2017.

So, final question: how highly correlated are the long-term trends in majority opinions, concurrences and dissents?  In other words – do longer majorities drive length in dissents, or vice versa?  (If the answer seems obvious, it isn’t, necessarily – earlier this week, we showed that majorities and dissents are only moderately correlated for that Court, and majorities and concurrences are almost entirely unrelated).

The answer for California is that there is at least moderately strong evidence that length in dissents and concurrences helps drive longer majorities.  For the entire period, the correlation between majorities and dissents is 0.561, and the correlation between majorities and concurrences in 0.415.  Has that result been consistent for the entire twenty-eight years?  Surprisingly, the answer is no.  For the years 2004 to 2017, dissents have had almost no influence on majorities at all – the correlation is only 0.0009.  There’s a moderate correlation between majority opinions and concurrences – 0.4011.  For the first half of the period – the years 1990 to 2003 – both correlations were significantly higher.  The correlation between majority opinions and dissents was 0.7964 – a very high number.  The correlation between majority opinions and concurrences was 0.5451.

Join us back here next week as we turn our attention to the Court’s criminal docket.

Image courtesy of Flickr by Damian Gadal (no changes).