[1] Born in Caroline County, Virginia, McKinney attended Charlotte Hall Military Academy in Maryland, and "apparently saw military service during the War of 1812",[1] and was indicated in one biography to have eventually held the rank of general,[2] although "no source for this rank has been found".
[3] McKinney read law to gain admission to the bar in Kentucky in 1815.
[3] At some point thereafter he moved to Indiana, where he was admitted to the Franklin County bar on March 3, 1822, becoming a prosecuting attorney in October of that year, and being commissioned as a captain in the Indiana Militia that same month.
[1] On January 28, 1831, Governor James B. Ray, who was friends with McKinney through their time practicing law before the same courts, appointed McKinney to a seat on the Indiana Supreme Court.
[3] At the time of his appointment, McKinney already suffered from tuberculosis, from which he died while still serving on the court, in Brookville.