By 1911, Johnstone was involved in a disagreement with league president Thomas Lynch related to umpiring an unsanctioned offseason series.

While working in the American Association in 1914, Johnstone's jaw was broken by a punch from pitcher Bill Burns.

[3] Johnstone umpired the July 31, 1908 Giants-Cardinals game in which Fred Tenney stole first base after having already reached second.

At the time no rule prevented this tactic and Johnstone allowed Tenney to remain on first base.

Johnstone's design would remain largely unchanged until the development of the hockey-style mask in the 21st century.