The companies listed on the United States’ major stock exchanges number 4,048. Quite plausibly, each of them has at least one in-house lawyer, if only to deal with Sarbanes-Oxley, SEC filings, and exchange requirements. If I had data on the proportion of US companies over a given revenue or number of employees that are publicly traded, I could go farther in my estimates of the number of law departments in US companies.
In addition, reports the NY Times, Nov. 18, 2010, at B6, Chinese stock exchanges cover 3,019 companies. For both facts, the Times cites the World Federation of Exchanges. The WFE website, which draws on 52 exchanges, displays the total number of companies listed as 10,315 for the Americas; 20,954 for Asia/Pacific; and 13,790 for EMEA – a total of 45,059 traded companies (many may be listed on more than one exchange). Doesn’t that conservatively suggest at least 40,000 legal departments in the world?