I poked around on a site operated by the Library of Congress that has , compiled 1.2 million pages of American newspapers published between 1880 and 1922. Naturally, I searched the terms “legal department” and “law department.” “Legal department” returned 2,242 hits. Here is the earliest, from the New York Tribune, June 21, 1910.
“Every railroad maintains a legal department that gives plenty of employment for a varying number of lawyers, always, however, large. Questions are coming up all the time in railroad practice that the public never hears about, but the legal department of a railroad is one of its busiest, whether the fact becomes a matter of general knowledge or not. It is not only accidents that lead to claims that keep the railroad’s lawyers busy. Shippers and consignees have constant complaints to make of damage to freight, and an enormous number of cases of this sort have to be handled in the course of a year.”
The term “law department” returned twice as many hits, 4,722 results, in part because law departments of universities show up. The earliest substantive reference was from The Independent (Honolulu, H.I.), Feb. 17, 1904, Image 2, which referred to the law department of Hawaii in a tax issue (See my post of Dec. 31, 2006: early history of law departments in the US; and Dec. 31, 2006: NY Times articles on law departments.).