One of my blog posts drew on data from Portugal, USA, UK, and Belgium to estimate very roughly legal departments per billion dollars of GDP at 0.6, 0.7, 0.5, and 1.2 (See my post of May 10, 2010: four countries and GDP.). If we take as the lodestar the low end of 0.5, that says for every two billion dollars of Gross Domestic Product we might expect one law department. That touchstone seems very low, in that in several developed countries, figures like one internal lawyer for every $250 to $400 million (2-4 lawyers per billion of revenue) is typical, but GDP doesn’t arise only from corporations. In fact, about two out of every three GDP dollars comes from consumers (See my post of July 19, 2011: article on legal industry.).
Anyway, in Joseph Mazur, What’s Luck Got to Do with It? – The history, mathematics, and psychology of the gambler’s illusion (Princeton 2010) at 70, Mazur write that “the estimated value of the GDP of the whole world in 2008 was $54.3 trillion.” If we take 55 thousand billions as an updated estimate, and apply half a law department per billion, that suggests 25,000 law departments worldwide. It is quite certain there are two or three times more, so this string of conjectures has run out.