It is difficult to say what was the first law-related book devoted to sports law, but if the title is any indication, it could be W. M. Thompson and J. D. A. Johnson, The Law of Sports (1896), which was published by W. B. Hearnden of New Inn Chambers, London.  Its authors appear to have been British, or possibly Irish, barristers.  The Law Times for 1894 lists them as arguing the case of Keep v. The Vestry of St. Mary, Newington before Queen’s Bench, and their names appear as counsel in a number of criminal cases argued in Old Bailey (London’s central criminal court) in the 1890’s and the early 1900’s.

The Law of Sports is extremely difficult to locate; in fact, it appears that there is no known copy in the United States. This work was reviewed in the London Journal in 1896, and the following description of the work can be found on page 152 of Volume 13 of Fores’s Sporting Notes and Sketches,(London 1896) under the heading of “Notes on Novelties”:

The Law of Sports by W. M. Thompson and J. D. A. Johnson, LL.D., is a useful pamphlet, the copious information therein contained being summarised into the smallest possible space. The legal points connected with the game laws, fishing, hunting, racing, and gambling, being (so to speak) “in a nutshell.” Hearnden, New Inn Chambers, is the publisher.

Fores’s Sporting Notes and Sketches, which can be found in the New York Public Library, was a magazine containing articles “descriptive of British, Indian, Colonial, and Foreign Sport.”  Because Fores’s description makes no mention of team sports like cricket, rugby, or association football or of individual competitor sports like golf and tennis, it is conceivable that the Thompson and Johnson work is devoted only to what are often called “field sports.” 

If that is so, there are many older works on those topics, including George Putnam Smith, The Law of Field-Sports, which was published in 1886 by the New York publisher O. Judd Company, and Henry John Rous’ The Laws and Practices of Horse Racing (London 1866), which earned its author the appellation “the Blackstone of Horse Racing.”  Works on the law of hunting date back at least to the 18^th century.  Thomson Gale, The Game Laws was published in its 7^th edition in 1807.