[3] In private practice, Cox gained national attention assisting the prosecutor in the 1925 trial of D. C. Stephenson for the death of Madge Oberholtzer.

In addition to private practice and his tenure on the Indiana Supreme Court, Cox's legal career also included librarian of the Indiana State Law Library, Marion County Deputy Prosecuting Attorney, and city judge of Indianapolis.

[5] This particular branch of the Cox family was originally Quaker, and operated a mill on the Deep River in North Carolina, near the area that eventually became the city of Greensboro.

Because of Niblack's impaired eyesight, Cox was employed by the judge to read records, briefs, and law books.

[14] Cox was also appointed deputy prosecuting attorney of Marion County in 1891, and he served in that position until he became city judge of Indianapolis.

[18] First, the court agreed (in a split decision) with an injunction in the "Marshall Constitution" case (Ellingham vs. Dye) that the state legislature, working with Democratic Governor Thomas R. Marshall, did not have the power to propose both a state constitution and the method to adopt it.

The decision was split, with Cox siding with the two Republican members of the Indiana Supreme Court while the other two Democrats dissented.

[19] The "Technical Institute" (Richards v. Wilson) case is the other trial typically mentioned as significant during Cox's tenure.

[27] Cox was one of the chief prosecutors in the trial, and was quoted in the New York Times denouncing Stephenson as one who “holds himself above the law” and as a “destroyer of the virtue of women”.

Unable to get the pardon he expected, a vengeful Stephenson began naming politicians who had helped him gain power, resulting in jail time for the Indianapolis mayor and the resignation of other government officials.

[29] By 1930, Cox had moved to a country estate and farm on the northeast side of Indianapolis in Lawrence Township.

[1] A book described him “as an attorney one of the ablest, as a judge recognized by the people of all parties as one of the best jurists who ever sat as a member of the Supreme Court of the state of Indiana.”[32] On February 3, 1936, Cox became ill while at his office, and died that evening at St. Vincent Hospital.

The news of his death spread quickly throughout the state, and on the next day his picture was on the front page of the local newspaper in Indianapolis.