Soon after gaining admission to the bar in 1864, he moved to Kansas City, Missouri, and entered into the practice of law.

[1][2] He quickly developed a large law practice, and "figured prominently and creditably in a number of instances of exceedingly important litigation".

As a justice, his opinions were described as "concise, expressed in terse and vigorous phrases, and manifest a decided inclination to follow adjudged cases".

In one case, the court considered one of Black's own previous opinions from his tenure as a circuit judge.

[1] Black died at his home in Kansas City at a time when he was planning to step away from his excessive workload.