The NJ Law Journal published its “2011 Directory of In-House Counsel.” It lists 1,944 individual names. It lists them on 55 pages by company, but does not state the number of companies (i.e., law departments). To calculate that, I counted the number of companies on every other page for the first fourteen, found 12.6 companies on average per page, and therefore estimate about 700 departments (12.6 times 55 pages).
Coincidentally, an ad in the Directory for the New Jersey Chapter of the Association of Corporate Counsel (at 21) states that its membership directory has “more than 1,200 in-house counsel at more than 450 companies.” Since it costs to belong to the ACC, but not to be listed in the Directory and lawyers in the government are not allowed to be ACC members, it makes sense that the ACC chapter has about two-thirds as many lawyers and law departments. I have not cross checked membership against each other, but let’s assume overlap to a large degree, but not completely.
So, grant 2,000 in-house lawyers in New Jersey at 750 companies. The average therefore would be 2.7 lawyers per department. Meanwhile, New Jersey in 2010 had 8.8 million residents out of 308 million in the United States. So, at 84.3 law departments per million residents in the Garden State, the United States would extrapolate to 26,000 law departments.